# x402 shelves at x402tookit.com

> 148 focused, pay-per-call APIs (1298 endpoints) for AI agents and developers. Each call costs a few cents in USDC over x402; there is no account, signup or API key. Every answer is a computed verdict with the reasons, the source, and what was NOT checked.

## How to use
- Pick a shelf below. Each shelf is its own host: https://<shelf>.x402tookit.com
- GET /openapi.json on a shelf lists its endpoints, prices and parameters; GET /llms.txt describes it for models.
- Call an endpoint without paying and you receive HTTP 402 with the exact price and how to pay. Any x402 client (for example @x402/fetch) pays and retries automatically.
- Everything in one file: https://x402tookit.com/catalog.json

## Shelves
- [Airlines Reference](https://airlines-reference.x402tookit.com/llms.txt): Airline lookup by IATA or ICAO code, callsign, country and flight number parsing from the OpenFlights snapshot. (7 endpoints, $0.02 to $0.02)
- [Airports Reference](https://airports-reference.x402tookit.com/llms.txt): Airport lookup, nearest airports, distances, runways and hubs from OurAirports open data. (8 endpoints, $0.02 to $0.02)
- [Algebra and Geometry Solvers](https://math-geometry.x402tookit.com/llms.txt): Quadratic and cubic roots, triangle solver, shape areas and volumes, linear systems, matrices, vectors, trig, complex numbers, series, coordinate geometry. (11 endpoints, $0.02 to $0.02)
- [Audio Calc](https://audio-calc.x402tookit.com/llms.txt): Audio engineering maths for agents: sample rates, bit depth, bitrates, dB sums, SPL, LUFS, latency, tuning ratios and room modes. (12 endpoints, $0.02 to $0.02)
- [Automotive Calculators](https://automotive-calc.x402tookit.com/llms.txt): Car math for agents: tire size and speedometer error, gearing and RPM, trip fuel, EV efficiency, towing, depreciation, lease versus buy, engines and braking. (10 endpoints, $0.02 to $0.02)
- [Aviation Calculators](https://aviation-calc.x402tookit.com/llms.txt): Pilot math from your own numbers: pressure and density altitude, ISA, true airspeed, wind components, wind triangle, fuel and time, glide and turns. (9 endpoints, $0.02 to $0.02)
- [Aviation Weather](https://aviation-weather.x402tookit.com/llms.txt): Airport weather decoded into flight categories, forecast deterioration, crosswind, density altitude and SIGMET hazards. (8 endpoints, $0.02 to $0.03)
- [Bank and Tax ID Validators](https://bank-validators.x402tookit.com/llms.txt): Validate IBAN, BIC, card number, US routing, EU VAT and US EIN formats and check digits. (8 endpoints, $0.02 to $0.03)
- [Barcodes and QR Codes](https://barcode-qr.x402tookit.com/llms.txt): Generate QR, Code 128 and EAN-13 SVG barcodes, QR capacity, check digits and Wi-Fi or vCard payloads. (7 endpoints, $0.02 to $0.03)
- [Bicycle Gearing & Fit Calc](https://bike-calc.x402tookit.com/llms.txt): Gear ratios and speed, cadence, gear tables, chain length, wheel circumference, climb grades, saddle height and frame size. (8 endpoints, $0.02 to $0.02)
- [Bitcoin Network](https://bitcoin-network.x402tookit.com/llms.txt): Fee estimates, address and transaction status, network health, mining pools, supply and price from mempool.space. (8 endpoints, $0.02 to $0.03)
- [Books and Libraries](https://books-library.x402tookit.com/llms.txt): Book lookup by ISBN, book and author search, author works, subject lists, reading time and citation formatting from Open Library. (7 endpoints, $0.02 to $0.03)
- [Calendar Systems](https://calendar-systems.x402tookit.com/llms.txt): Date conversion and calendar facts for agents: Julian Day, Julian, Hebrew, Islamic tabular and Persian calendars, Chinese zodiac, moon phases and seasons. (12 endpoints, $0.02 to $0.02)
- [Cheap Utilities](https://cheap-utilities.x402tookit.com/llms.txt): Tiny deterministic helpers for agents: JSON repair and diff, cron and semver, hashes, contrast, URL, email, IP and timestamp checks, text stats. (12 endpoints, $0.02 to $0.02)
- [Chemistry Calculators](https://chemistry-calc.x402tookit.com/llms.txt): Periodic table lookup, molar mass from formulas, mole conversions, dilution, pH, ideal gas, limiting reagent, empirical formula, bond polarity, half-life. (11 endpoints, $0.02 to $0.02)
- [Chess Notation Tools](https://chess-notation.x402tookit.com/llms.txt): FEN validation and parsing, square maths, empty-board piece moves, material count, PGN tag parsing and time-control categories. (8 endpoints, $0.02 to $0.02)
- [Chinese Calendar and Culture](https://chinese-culture.x402tookit.com/llms.txt): Solar terms, lunar dates, BaZi pillars, I Ching hexagrams, hanzi pinyin and simplified/traditional conversion. (7 endpoints, $0.02 to $0.03)
- [Classic Ciphers and Encodings](https://text-ciphers.x402tookit.com/llms.txt): Caesar, Vigenere, Playfair, rail fence, Morse, NATO, Braille, Base32/58/64 and frequency analysis for puzzles and learning. (10 endpoints, $0.02 to $0.02)
- [Color and Design Tools](https://color-design.x402tookit.com/llms.txt): Exact color conversion, accessible text colors, palettes, mixing, color-blindness simulation and contrast fixes. (8 endpoints, $0.02 to $0.02)
- [Company Enrichment](https://company-enrichment.x402tookit.com/llms.txt): Company profiles, filings, 8-K red flags, insider trades, financials and legal-entity data from SEC EDGAR and GLEIF. (11 endpoints, $0.02 to $0.05)
- [Construction Calculators](https://construction-calc.x402tookit.com/llms.txt): Materials and layout maths for concrete, paint, stairs, roofs, lumber, tile, drywall, fences and decks. (10 endpoints, $0.02 to $0.02)
- [Cooking Calculators](https://cooking-calc.x402tookit.com/llms.txt): Kitchen math for agents: recipe scaling, safe temperatures, ovens, baker's percentages, yeast, eggs, pans, brine, ABV and coffee. (12 endpoints, $0.02 to $0.02)
- [Country and Currency Codes](https://country-codes-iso.x402tookit.com/llms.txt): ISO 3166 countries, ISO 4217 currencies, ISO 639 languages, calling codes and TLDs as an offline reference. (10 endpoints, $0.02 to $0.02)
- [Country Facts](https://country-facts.x402tookit.com/llms.txt): Borders, driving side, time zones, land routes and comparisons for 250 countries and territories. (8 endpoints, $0.02 to $0.02)
- [Craft & Maker Calc](https://craft-calc.x402tookit.com/llms.txt): Cross-stitch size, quilt binding, knitting gauge, half-square triangles, candle wax, resin volume, stitch counts and decal scaling. (8 endpoints, $0.02 to $0.02)
- [Crypto Math](https://crypto-math.x402tookit.com/llms.txt): Modular arithmetic, primality, CRT, curve parameters, RSA sizing, encodings, entropy and check digits. (10 endpoints, $0.02 to $0.02)
- [CSS Design Calc](https://css-design-calc.x402tookit.com/llms.txt): CSS and layout maths for agents: unit conversion, fluid clamp(), type scales, aspect ratios, grids, specificity and readability. (12 endpoints, $0.02 to $0.02)
- [DeFi Intelligence](https://defi-intel.x402tookit.com/llms.txt): DeFi yields, protocol TVL moves, stablecoin pegs, hacks and fees computed from DefiLlama public data. (10 endpoints, $0.02 to $0.05)
- [Dev Reference](https://dev-reference.x402tookit.com/llms.txt): Developer reference lookups for agents: HTTP status codes, headers, CSP and Cache-Control explainers, MIME types, ports, DNS record types, ISO 8601 and Unicode. (12 endpoints, $0.02 to $0.02)
- [Developer Utilities](https://dev-utils.x402tookit.com/llms.txt): JWT decoding, iCalendar builder, breached-password check, certificate transparency, cron schedules, regex tester, user-agent parser. (7 endpoints, $0.02 to $0.02)
- [Dictionary and Etymology](https://dictionary-wiktionary.x402tookit.com/llms.txt): English word definitions, pronunciation, etymology, inflections and translations from Wiktionary. (7 endpoints, $0.02 to $0.03)
- [Domain and DNS Checks](https://domain-dns.x402tookit.com/llms.txt): DNS records, email authentication, DNSSEC, CAA, registration data and email address checks. (9 endpoints, $0.02 to $0.05)
- [Electrical Calculators](https://electrical-calc.x402tookit.com/llms.txt): Voltage drop, three-phase power, power factor correction, transformer sizing, wire resistance, energy cost, AC impedance and battery banks. (8 endpoints, $0.02 to $0.02)
- [Electronics Calculators](https://electronics-calc.x402tookit.com/llms.txt): Ohm's law, resistor codes and standard values, dividers, LED resistors, RC filters, battery runtime, wire gauge, decibels, 555 timers, power cost. (11 endpoints, $0.02 to $0.02)
- [Emoji Tools](https://emoji-tools.x402tookit.com/llms.txt): Emoji search, info, skin tones, flags, text analysis and shortcodes from Unicode emoji data. (8 endpoints, $0.02 to $0.03)
- [Environment Screen](https://environment-screen.x402tookit.com/llms.txt): Air quality, pollen, AQI conversion and EPA toxics-release facility screens for a place. (8 endpoints, $0.02 to $0.05)
- [EVM Chains Read-Only](https://evm-chains.x402tookit.com/llms.txt): Live read-only facts from public RPCs for Ethereum, Base, Arbitrum, Optimism and Polygon. (9 endpoints, $0.02 to $0.03)
- [Farm & Garden Calc](https://agri-calc.x402tookit.com/llms.txt): Growing degree days, ET0, plant counts, fertilizer maths, lime, irrigation time, feed and stocking arithmetic. (10 endpoints, $0.02 to $0.02)
- [File Format Inspector](https://file-formats.x402tookit.com/llms.txt): Identify and inspect files from their first bytes: magic numbers, PNG, JPEG, GIF, WebP, ZIP, gzip and PDF headers. (9 endpoints, $0.02 to $0.02)
- [Finance Calculators](https://finance-calculators.x402tookit.com/llms.txt): Exact loan, savings, growth, break-even and cash-flow calculations for agents, with no model guesswork. (9 endpoints, $0.02 to $0.02)
- [Fitness and Body Calculators](https://fitness-calc.x402tookit.com/llms.txt): BMI, ideal weight, calorie needs, macros, one-rep max, heart-rate zones, race pace and prediction, body fat, calorie burn, due date. (10 endpoints, $0.02 to $0.02)
- [Focus & Sleep Planner](https://focus-sleep-calc.x402tookit.com/llms.txt): Sleep-cycle bedtimes, caffeine decay, Pomodoro and nap schedules, sleep tally, jet-lag shifts and time blocks. (7 endpoints, $0.02 to $0.02)
- [Food Barcode Facts](https://food-barcode.x402tookit.com/llms.txt): Packaged food lookup by barcode: nutrition, allergens, diet fit, additives, comparison, daily values. (7 endpoints, $0.02 to $0.05)
- [FX Rates ECB](https://fx-ecb.x402tookit.com/llms.txt): Currency rates, conversion, history, volatility and movers from European Central Bank reference rates. (8 endpoints, $0.02 to $0.02)
- [Garden Calculators](https://garden-calc.x402tookit.com/llms.txt): Garden math for agents: growing degree days, plant spacing, bed soil, drip irrigation, fertilizer, compost balance, frost risk and planting dates. (8 endpoints, $0.02 to $0.02)
- [Geo Calc](https://geo-calc.x402tookit.com/llms.txt): Coordinate math for agents: geohash, Plus Codes, UTM and MGRS, geodesics, bounding boxes, polygon area and coordinate formats. (12 endpoints, $0.02 to $0.02)
- [Global Hazards](https://global-hazards.x402tookit.com/llms.txt): Worldwide earthquakes, storms, volcanoes and other natural hazard events from keyless public feeds, plus quake and seismic-wave calculators. (10 endpoints, $0.02 to $0.05)
- [Global Weather](https://weather-global.x402tookit.com/llms.txt): Worldwide forecasts for any coordinates: now, daily, rain, wind, UV and outdoor conditions, plus heat index, wind chill and dew point. (9 endpoints, $0.02 to $0.05)
- [Grades & Study Calc](https://grades-calc.x402tookit.com/llms.txt): Grade needed on a final, weighted grades, GPA, percent to letter, curves, percentile rank, reading plans and study time. (8 endpoints, $0.02 to $0.02)
- [Graph Algorithms](https://graph-algorithms.x402tookit.com/llms.txt): Shortest paths, spanning trees, topological order, components, max flow, graph statistics and all-pairs distances from a caller-supplied edge list. (8 endpoints, $0.02 to $0.03)
- [Hacker News](https://hacker-news.x402tookit.com/llms.txt): Hacker News stories, search, threads, users, domain stats and trending topics. (7 endpoints, $0.02 to $0.03)
- [Home Energy Calculators](https://home-energy-calc.x402tookit.com/llms.txt): Home energy math for agents: bills, appliance loads, solar sizing, heat loss, HVAC load checks, insulation, water heating, EV charging and fuel cost. (9 endpoints, $0.02 to $0.02)
- [HVAC Airflow & Load Calc](https://hvac-calc.x402tookit.com/llms.txt): Airflow heat load, air changes, duct sizing, velocity, fan laws, efficiency conversions and mixed-air temperature. (7 endpoints, $0.02 to $0.02)
- [Hydrology & Open-Channel Calc](https://hydrology-calc.x402tookit.com/llms.txt): Manning flow, normal and critical depth, Froude number, weir flow, rational method, time of concentration and orifice flow. (8 endpoints, $0.02 to $0.03)
- [Identifier Validators](https://id-validators.x402tookit.com/llms.txt): Check digits and structure for ISBN, UPC/EAN, VIN, ISSN, ORCID, ISIN, CUSIP, LEI and MAC addresses. (9 endpoints, $0.02 to $0.02)
- [Industry and Occupation Codes](https://industry-occupation-codes.x402tookit.com/llms.txt): NAICS 2022 industry codes and SOC 2018 occupation codes: lookup, search, hierarchy and industry-occupation links from Census and BLS. (8 endpoints, $0.02 to $0.03)
- [International Address Formats](https://address-formats.x402tookit.com/llms.txt): Postal address formats, postal-code validation and subdivisions for about 240 countries from a bundled Google i18n snapshot. (8 endpoints, $0.02 to $0.02)
- [Investing Math](https://invest-math.x402tookit.com/llms.txt): Position sizing, drawdowns, Sharpe, DCA, dividends, FIRE and option payoffs for trading bots and planners. (12 endpoints, $0.02 to $0.02)
- [Jewelry Maker Calc](https://jewelry-calc.x402tookit.com/llms.txt): Ring size conversion, bead counts, necklace and bracelet lengths, metal weight, carat estimates, karat alloy mixing and melt value. (8 endpoints, $0.02 to $0.02)
- [JSON and Data Tools](https://json-data-tools.x402tookit.com/llms.txt): Validate, format, diff, query and convert JSON, CSV, encodings and hashes. (9 endpoints, $0.02 to $0.02)
- [Land Survey Screening](https://land-survey.x402tookit.com/llms.txt): Elevation, slope, flood zone and wetlands screening for any US coordinate, plus distance, area and sun-time helpers. (8 endpoints, $0.02 to $0.05)
- [License Intel](https://license-intel.x402tookit.com/llms.txt): Look up, search, parse and compare open-source licenses from the SPDX list and plain-language rules. (9 endpoints, $0.02 to $0.03)
- [Life Dates & Milestones](https://life-dates.x402tookit.com/llms.txt): Exact age, next birthday, 1,000-day milestones, weekday of any date, zodiac signs, birthstones and generations. (8 endpoints, $0.02 to $0.02)
- [Linear Algebra](https://linear-algebra.x402tookit.com/llms.txt): Matrix multiply, determinant, inverse, rank, linear solve, eigenvalues, vector ops, least squares and transforms. (10 endpoints, $0.02 to $0.02)
- [LLM Cost & Capacity Calc](https://llm-cost-calc.x402tookit.com/llms.txt): Token estimates, API cost, prompt-cache savings, batch discounts, context fit, rate-limit planning and model comparison from your own prices. (8 endpoints, $0.02 to $0.02)
- [LLM Model Intelligence](https://llm-models.x402tookit.com/llms.txt): Compare AI model prices, context and capabilities, estimate costs, and check open-model licenses and activity. (8 endpoints, $0.02 to $0.02)
- [Locale and Formatting Tools](https://locale-tools.x402tookit.com/llms.txt): Locale-aware number, currency, date, plural, relative-time, list and sort formatting from the ICU/CLDR data built into the server. (8 endpoints, $0.02 to $0.02)
- [Machine Learning Metrics](https://ml-metrics.x402tookit.com/llms.txt): Classification, ranking, regression, calibration and text-generation metrics computed exactly from arrays you send. (8 endpoints, $0.02 to $0.02)
- [Machining & Fasteners Calc](https://machining-calc.x402tookit.com/llms.txt): Spindle speeds, feeds, metal removal, tap drills, thread geometry, bolt torque and sheet-metal bends. (8 endpoints, $0.02 to $0.02)
- [Map Tile Maths](https://map-tiles.x402tookit.com/llms.txt): Web Mercator and slippy-map tile maths: tile numbers, bounds, quadkeys, ground resolution, zoom for an extent, tile counts and scale. (8 endpoints, $0.02 to $0.02)
- [Marine Conditions](https://marine-conditions.x402tookit.com/llms.txt): Tide predictions, water level and surge, buoy observations, nearest stations, Beaufort and sea state. (7 endpoints, $0.02 to $0.03)
- [Market and Holiday Calendar](https://market-calendar.x402tookit.com/llms.txt): NYSE trading calendar, early closes, option expirations, trading days, and public holidays for 100 countries. (9 endpoints, $0.02 to $0.02)
- [Markup and Text Extraction Tools](https://markup-tools.x402tookit.com/llms.txt): Turn HTML and Markdown you supply into text, links, headings, tables, metadata and main-content extracts. (8 endpoints, $0.02 to $0.03)
- [Math and Statistics](https://math-stats.x402tookit.com/llms.txt): Descriptive statistics, correlation, probability distributions, confidence intervals, t-tests, A/B tests, sample sizes, combinatorics and number theory. (10 endpoints, $0.02 to $0.02)
- [Medical Codes and Drug Names](https://medical-codes.x402tookit.com/llms.txt): Look up ICD-10-CM diagnosis codes, HCPCS, LOINC lab codes and RxNorm drug names, plus code format checks. (8 endpoints, $0.02 to $0.05)
- [Music Production Calc](https://music-production-calc.x402tookit.com/llms.txt): Studio arithmetic: tempo grids, song length, tap tempo, key shifts and capo, Camelot mixing, diatonic chords, fretboard notes, pitch-speed and delay tails. (9 endpoints, $0.02 to $0.02)
- [Music Theory](https://music-theory.x402tookit.com/llms.txt): Notes, frequencies, intervals, scales, chords, keys, transposition, tempo math and Roman numeral analysis. (10 endpoints, $0.02 to $0.02)
- [NASA Exoplanets](https://exoplanets-nasa.x402tookit.com/llms.txt): Confirmed exoplanets from the NASA Exoplanet Archive: planet and star lookups, habitable-zone screens, discovery stats, nearest planets and calculators. (10 endpoints, $0.02 to $0.03)
- [NASA Media Library](https://nasa-media.x402tookit.com/llms.txt): Search NASA's Image and Video Library: photos, video and audio with dates, centers, rights fields and asset files. (8 endpoints, $0.02 to $0.05)
- [Network Calc](https://network-calc.x402tookit.com/llms.txt): Network engineering maths for agents: subnetting, IPv6 formats, CIDR aggregation, bandwidth, TCP windows, MTU and VoIP. (12 endpoints, $0.02 to $0.02)
- [Network Intel](https://network-intel.x402tookit.com/llms.txt): Who runs an IP or ASN, is a route valid, abuse contacts, routing visibility, CIDR math. (9 endpoints, $0.02 to $0.05)
- [Number Words](https://number-words.x402tookit.com/llms.txt): Numbers to words and back: English, Spanish, French, German, Roman numerals, cheque amounts, years and ordinals. (9 endpoints, $0.02 to $0.02)
- [Package Health](https://package-health.x402tookit.com/llms.txt): Open-source package health: activity, abandonment, deprecation, license class, dependency weight and build provenance. (8 endpoints, $0.02 to $0.03)
- [Package Registries](https://package-registries.x402tookit.com/llms.txt): Health checks for Rust crates, Ruby gems, PHP packages, NuGet, Go modules, Homebrew formulae and Docker images, plus SPDX license classification. (8 endpoints, $0.02 to $0.05)
- [Paper & Print Calc](https://paper-print-calc.x402tookit.com/llms.txt): ISO and US paper sizes, print pixels at a dpi, sheet fitting, paper weight, envelope fit, typographic units and book signatures. (8 endpoints, $0.02 to $0.02)
- [Party & Event Planner](https://party-event-calc.x402tookit.com/llms.txt): Food, drinks, ice, seating, timeline, bill split, pizza, cake and budget rule-of-thumb arithmetic for events. (9 endpoints, $0.02 to $0.02)
- [Perp Derivatives Signals](https://derivatives.x402tookit.com/llms.txt): Crypto perpetual futures funding, open interest, basis, liquidity and crowding signals. (11 endpoints, $0.02 to $0.02)
- [Pet Care Calc](https://pet-calc.x402tookit.com/llms.txt): Pet energy needs, food portions, dog age conversions, aquarium volume and weight, water changes and feeding schedules. (8 endpoints, $0.02 to $0.02)
- [Phone Number Tools](https://phone-tools.x402tookit.com/llms.txt): Parse, validate and format phone numbers worldwide from bundled libphonenumber metadata, with no dependency. (8 endpoints, $0.02 to $0.02)
- [Photography Calculators](https://photo-calc.x402tookit.com/llms.txt): Exposure value and trades, depth of field, field of view, crop factor, ND filters, handheld and star-trail rules, print size, sunny 16, flash and time-lapse. (11 endpoints, $0.02 to $0.02)
- [Physics Calculators](https://physics-calc.x402tookit.com/llms.txt): Exact physics formulas for agents: kinematics, projectiles, inclines, collisions, orbits, oscillators, waves, optics, relativity and blackbody radiation. (12 endpoints, $0.02 to $0.02)
- [Places Near You (OpenStreetMap)](https://osm-places.x402tookit.com/llms.txt): Nearby shops, health, fuel, EV charging and transit from OpenStreetMap, with distance and bearing. (7 endpoints, $0.02 to $0.03)
- [Plumbing & Pipe Flow Calc](https://plumbing-calc.x402tookit.com/llms.txt): Pipe volume, flow velocity, Hazen-Williams pressure loss, pipe sizing by velocity, thermal expansion, drain slope, tank fill time and bucket flow tests. (8 endpoints, $0.02 to $0.02)
- [Portfolio Stats](https://portfolio-stats.x402tookit.com/llms.txt): Return, risk and drawdown statistics computed on a price or return series that you supply. (10 endpoints, $0.02 to $0.02)
- [Prediction Market Signals](https://prediction-markets.x402tookit.com/llms.txt): Prediction market odds, liquidity quality, event coherence and cross-venue gaps from Polymarket and Kalshi public data. (9 endpoints, $0.02 to $0.02)
- [Pricing Math](https://pricing-math.x402tookit.com/llms.txt): Markup and margin, break-even, discount stacking, tiers, price rounding, bundles, MRR and fee-inclusive pricing. (9 endpoints, $0.02 to $0.02)
- [Probability Calculators](https://probability-calc.x402tookit.com/llms.txt): Dice, card and lottery odds, multinomials, expected value, exact distribution tables, gambler's ruin, Bayes and streaks. (10 endpoints, $0.02 to $0.02)
- [Public Domain Books](https://public-domain-books.x402tookit.com/llms.txt): Search Project Gutenberg's free books by title, author, topic and language, with download links. (7 endpoints, $0.02 to $0.02)
- [Publishing Calc](https://publishing-calc.x402tookit.com/llms.txt): Self-publishing arithmetic: page counts, reading and audiobook time, spine and cover size, trim sizes, royalties and ebook size. (9 endpoints, $0.02 to $0.02)
- [Puzzle Solvers](https://puzzle-solvers.x402tookit.com/llms.txt): Bounded solvers and checkers for sudoku, N-queens, Tower of Hanoi, magic squares, Game of Life, sliding puzzles and knight's tours. (8 endpoints, $0.02 to $0.02)
- [Radio & RF Calc](https://radio-calc.x402tookit.com/llms.txt): Maidenhead grid squares, path loss, link budgets, Fresnel zones, antenna length, SWR, dBm conversion, Morse and phonetic spelling. (9 endpoints, $0.02 to $0.02)
- [Recurrence Rules (RRULE)](https://recurrence-rules.x402tookit.com/llms.txt): Expand, parse, build and describe iCalendar RRULE recurrences, plus weekday and business-day patterns. (8 endpoints, $0.02 to $0.03)
- [Research Paper Checks](https://research-papers.x402tookit.com/llms.txt): Verify citations, catch retracted papers, and profile papers, authors, journals and institutions from Crossref and OpenAlex. (8 endpoints, $0.02 to $0.03)
- [RSS and Atom Feed Reader](https://feed-reader.x402tookit.com/llms.txt): Read, search, validate, merge and discover RSS 1.0, RSS 2.0 and Atom 1.0 feeds and podcast episode lists. (8 endpoints, $0.03 to $0.05)
- [Satellite Catalog](https://satellite-catalog.x402tookit.com/llms.txt): CelesTrak satellite search, orbital elements, orbit classification and decay screens. (7 endpoints, $0.02 to $0.03)
- [Scripture Lookup](https://scripture.x402tookit.com/llms.txt): Public-domain Bible verses and passages, verse of the day, book table and reference parser. (7 endpoints, $0.02 to $0.03)
- [SEC Filing Search](https://sec-search.x402tookit.com/llms.txt): Full-text search of SEC filings, recent IPO and going-concern filings, ticker lookup and filing URL tools. (6 endpoints, $0.02 to $0.03)
- [Security Math](https://security-math.x402tookit.com/llms.txt): Password entropy, crack-time ranges, NIST key sizes, collision odds, Bloom filter sizing, checksums and Shamir threshold maths. (8 endpoints, $0.02 to $0.02)
- [Shipping & Logistics Calc](https://shipping-calc.x402tookit.com/llms.txt): Dimensional weight, CBM, box and pallet packing, container load, landed cost and unit-price maths. (8 endpoints, $0.02 to $0.02)
- [Site Climate](https://site-climate.x402tookit.com/llms.txt): Solar, wind, rainfall and temperature normals for any coordinates, plus daylength, altitude effects and Koppen class. (10 endpoints, $0.02 to $0.05)
- [Solana RPC Read-Only](https://solana-rpc.x402tookit.com/llms.txt): Live read-only facts from Solana mainnet's public RPC: slot, balances, accounts, tokens and fees. (9 endpoints, $0.02 to $0.03)
- [Space Objects](https://space-objects.x402tookit.com/llms.txt): Asteroids, comets, close approaches, fireballs and impact-risk lookups from NASA JPL, plus asteroid size, orbit and impact-scale calculators. (10 endpoints, $0.02 to $0.02)
- [Space Weather](https://space-weather.x402tookit.com/llms.txt): Solar flares, geomagnetic storms, aurora chances and radio and GPS impact from NOAA's Space Weather Prediction Center. (8 endpoints, $0.02 to $0.03)
- [Species and Biodiversity](https://biodiversity.x402tookit.com/llms.txt): Species name matching, taxonomy, conservation status, ranges and nearby wildlife sightings from GBIF. (8 endpoints, $0.02 to $0.05)
- [Sports Calculators](https://sports-calc.x402tookit.com/llms.txt): Ratings, sabermetrics, handicaps, odds, brackets and scoring for sports bots and fantasy tools. (12 endpoints, $0.02 to $0.02)
- [Star Catalog](https://star-catalog.x402tookit.com/llms.txt): Look up bright and nearby stars, cone searches, constellations, distances, luminosity and visibility by latitude. (8 endpoints, $0.02 to $0.02)
- [Statistical Tests](https://stats-tests.x402tookit.com/llms.txt): Chi-square, ANOVA, Mann-Whitney, Fisher exact, binomial and paired t-tests, multiple-comparison corrections, effect sizes, power and normality. (10 endpoints, $0.02 to $0.02)
- [Structural and Beam Calculators](https://structural-calc.x402tookit.com/llms.txt): Closed-form beam, section, column, stress, bolt and torsion formulas with typical material values, in SI or US units. (8 endpoints, $0.02 to $0.02)
- [Sun, Moon and Planets](https://sky-calc.x402tookit.com/llms.txt): Sun and Moon position, rise and set, twilight, planets, equation of time and eclipse checks. (8 endpoints, $0.02 to $0.03)
- [Systems Capacity Calculators](https://data-calc.x402tookit.com/llms.txt): Big-O growth, RAID capacity, storage growth, latency and throughput budgets, Little's law, queueing, Erlang and SLA downtime. (10 endpoints, $0.02 to $0.02)
- [Text Analysis Tools](https://text-metrics.x402tookit.com/llms.txt): Readability formulas, language guess, keywords, text similarity and diff, case conversion, SMS and tweet length limits. (7 endpoints, $0.02 to $0.02)
- [Text Similarity](https://text-similarity.x402tookit.com/llms.txt): String and text comparison: edit distance, Jaro-Winkler, LCS, n-gram, cosine, Soundex, Metaphone, diff and fuzzy ranking. (10 endpoints, $0.02 to $0.02)
- [Thermodynamics and Heat Transfer](https://thermo-heat-calc.x402tookit.com/llms.txt): Ideal gas processes, Carnot efficiency and COP, conduction, convection and radiation, heat exchangers, mixing, water vapor pressure and thermal expansion. (8 endpoints, $0.02 to $0.03)
- [Time Series Calculators](https://time-series-calc.x402tookit.com/llms.txt): Moving averages, exponential smoothing, autocorrelation, outliers, decomposition, growth rates, change points and forecast accuracy for a list of numbers. (8 endpoints, $0.02 to $0.03)
- [Time Zones and Dates](https://timezone-time.x402tookit.com/llms.txt): Exact time zone conversion, DST transitions, meeting overlap, business days, date differences and ISO weeks. (9 endpoints, $0.02 to $0.02)
- [Token Safety Checks](https://token-safety.x402tookit.com/llms.txt): On-chain safety facts about Base tokens, wallets and approvals, read straight from the chain. (8 endpoints, $0.02 to $0.02)
- [Trade and Customs Reference](https://trade-reference.x402tookit.com/llms.txt): Harmonized System codes, Incoterms 2020 rules and UN/LOCODE ports and trade locations for trade and customs work. (8 endpoints, $0.02 to $0.03)
- [UK Open Data](https://uk-open-data.x402tookit.com/llms.txt): UK postcodes, police crime data and bank holidays from free government sources. (9 endpoints, $0.02 to $0.03)
- [Unicode Text Safety Tools](https://unicode-text-tools.x402tookit.com/llms.txt): Hidden-character, bidi, confusable, script-mix, normalization and grapheme checks for text an agent is about to trust. (8 endpoints, $0.02 to $0.02)
- [Units and Conversions](https://units-convert.x402tookit.com/llms.txt): Exact unit, cooking, fuel, data-size, duration, number and base conversions, plus heat index and wind chill. (9 endpoints, $0.02 to $0.02)
- [URL & Text Tools](https://url-text-tools.x402tookit.com/llms.txt): URL parsing, RFC 3986 resolution, normalization, percent-encoding, punycode, slugs and tracking-parameter cleanup. (8 endpoints, $0.02 to $0.02)
- [US Counties and FIPS](https://us-counties.x402tookit.com/llms.txt): County FIPS codes, names, areas, populations, centroids and density from US Census Bureau data. (8 endpoints, $0.02 to $0.02)
- [US Geography](https://geo-us.x402tookit.com/llms.txt): Geocode US addresses, reverse geocode, districts, metro areas, ZIP lookup, state FIPS and GEOID parsing. (8 endpoints, $0.02 to $0.05)
- [US Tax Calculators](https://us-tax-calc.x402tookit.com/llms.txt): Federal income tax, FICA, capital gains, deduction and retirement-limit estimates from IRS published figures. (8 endpoints, $0.02 to $0.03)
- [US Treasury Macro](https://treasury-macro.x402tookit.com/llms.txt): US national debt, Treasury yield curve, average interest rates, interest expense and Treasury exchange rates from US Treasury data. (6 endpoints, $0.02 to $0.02)
- [Vehicle VIN Toolkit](https://vehicle-vin.x402tookit.com/llms.txt): Decode and validate VINs, look up manufacturers, makes and models from NHTSA vPIC, plus pure VIN structure tools. (9 endpoints, $0.02 to $0.02)
- [Video & Timecode Calc](https://video-calc.x402tookit.com/llms.txt): SMPTE timecode including drop-frame, shutter angle, slow motion, 2:3 pulldown, frame rates, resolution and bitrate maths. (8 endpoints, $0.02 to $0.02)
- [Vulnerability Intelligence](https://vuln-intel.x402tookit.com/llms.txt): Known vulnerabilities, exploited-in-the-wild status and exploit probability for software packages and CVEs. (8 endpoints, $0.02 to $0.05)
- [Web Page Extract](https://web-extract.x402tookit.com/llms.txt): Fetch a public web page and get clean Markdown, text, links, metadata, headings, tables and structured data. (8 endpoints, $0.03 to $0.05)
- [Web Probe](https://web-probe.x402tookit.com/llms.txt): Redirect trace, security headers, robots.txt, sitemap, TLS expiry, timing and meta tags for a URL you name. (7 endpoints, $0.02 to $0.02)
- [Web3 Tools](https://web3-tools.x402tookit.com/llms.txt): Check and decode crypto addresses, hashes, selectors and units without a node. (12 endpoints, $0.02 to $0.02)
- [Wikidata Facts](https://wikidata-facts.x402tookit.com/llms.txt): Entities, country, city and person profiles, identifier lookups and same-as links from Wikidata. (8 endpoints, $0.02 to $0.04)
- [Wikipedia Attention](https://wikipedia-attention.x402tookit.com/llms.txt): What the world is reading: page views, trending pages, comparisons, edit activity, summaries, search and on-this-day events. (8 endpoints, $0.02 to $0.05)
- [Word Tools](https://word-tools.x402tookit.com/llms.txt): Rhymes, synonyms, patterns, collocations and word-game scoring for writers and agents. (12 endpoints, $0.02 to $0.02)
- [Work Time Calc](https://work-time-calc.x402tookit.com/llms.txt): Business days, working hours, durations, overtime, timesheets, pay periods, ISO weeks and tenure arithmetic. (9 endpoints, $0.02 to $0.02)
- [World Bank Country Data](https://world-bank.x402tookit.com/llms.txt): Country economic and social indicators compared, trended and screened from World Bank open data. (7 endpoints, $0.02 to $0.03)
- [World Cities](https://world-cities.x402tookit.com/llms.txt): World cities of 15,000+ people: lookup, search, nearby, largest, time zones, distance and comparison from GeoNames. (8 endpoints, $0.02 to $0.03)
- [x402 Market Intelligence](https://x402-meta.x402tookit.com/llms.txt): Who sells what on x402, at what price, with what real traction, and whether an endpoint is payable and listable. (9 endpoints, $0.02 to $0.03)