the402 x402 endpoint directory

🆕 The next nonce for any Base address, plus its ETH balance and whether it is a contract. The count means different t

🆕 One block on Base — height, hash, parent, timestamp and age in seconds, transaction count, gas used against the lim

Reads the receipt of a transaction on Ethereum, Base, Base Sepolia, OP Mainnet, Arbitrum One, Polygon PoS or Avalanche

A stateless rule check for agents that pay for x402 endpoints. You supply the proposed payment, your policy and the am

Returns the raw public trade tape of Binance, Coinbase, Kraken, OKX or Bybit for one BASE/QUOTE pair, oldest first, ex

Returns the visible order book of Binance, Coinbase, Kraken, OKX or Bybit for one BASE/QUOTE pair. Levels come as [pri

Reads the public perpetual data of Binance USDⓈ-M Futures, Bybit linear and OKX swaps for one BASE/QUOTE pair. Settlem

Reads one transaction hash on Ethereum, Base, Arbitrum, Optimism, Polygon or BNB Smart Chain and answers the question

A symbol is not an identity. Dozens of contracts carry the symbol USDC and most of them are not the one anyone means.

Reads the fee history of the last 20 blocks on Ethereum, Base, Arbitrum, Optimism, Polygon or BNB Smart Chain and retu

A stateful duplicate check for agents that settle x402 payments. Supply any of payment_id, payload_hash and nonce; eac

Inspect up to 200 IP addresses at 0.0005 USDC per address.

Validates a 402 challenge — fetched from a URL without paying, or supplied directly — against PaymentRequiredV1Schema

Fetches the 402 challenge of a foreign endpoint without paying anything — no payment header, no signature, no settleme

Extract clean markdown text from a PDF (text-layer PDFs; no OCR). Turns a document an agent can't cheaply read into co

One featured space image or video per day, with a written explanation, media type, and direct image URL, as structured

Today's (or any past day's) featured astronomy picture — title, plain-language explanation, media type (image or video

The daily featured astronomy image or video, with title, explanation text, media type, and image URL, as normalized JS

Astronomy picture of the day API: one featured space image or video per day — title, plain-language explanation, media

Random draws from a curated advanced-English word list, one to ten at a time, each entry carrying part of speech, a pr

GRE and SAT vocabulary practice API: draws from 150 curated high-difficulty words — perspicacious, recalcitrant, ephem

Random advanced English word with everything needed to teach it: dictionary-quality definition, part of speech, exampl

Vocabulary builder serving GRE/SAT-caliber words: each entry has a precise definition, part of speech, natural example

Slang lookup and browse API: query a specific term or sample random entries from one generation's vocabulary — each en

What does that gen-z or gen-alpha term actually mean? Curated slang glossary with meaning, era, and example usage per

Translate slang across generations: send any term — rizz, no cap, adulting, gnarly, groovy — and get its plain-English

Generational slang dictionary spanning boomer to gen-alpha: look up what a slang term means (with origin generation, e

Machine-readable English dictionary entry by word: definitions across senses, part-of-speech tags, phonetic pronunciat

Get dictionary definitions for a word — all senses labeled noun/verb/adjective, with pronunciation guide and a synonym

Look up what an English word means: every dictionary sense with its part of speech, plus pronunciation, syllables, syn

English dictionary API: definitions with part of speech, pronunciation, syllable count, synonyms, and antonyms for any

Analyze a chess FEN string: turn to move, complete legal-move list, and terminal-state detection including checkmate,

Check whether a chess move is legal in a given FEN position and get the board state after it: resulting FEN, capture i

List every legal chess move for a position given as FEN, in both SAN (Nf3) and UCI (g1f3) notation, plus turn and chec

Chess position analysis from a FEN string: every legal move in SAN and UCI notation, whose turn it is, and full game-s

Returns rhyming words, sound-alikes, or commonly paired adjectives for any input word, ranked by strength of associati

Finds words related to any input word, similar meanings, words that sound alike, or adjectives commonly paired with it

Word association API: synonyms, rhymes, similar-sounding words, or strongly-associated terms for any word, ranked by s

Word association API: get words related to any word — meanings-like (ml), rhymes (rel_rhy), sounds-like (sl), or adjec

Daily history facts API: retrieves notable historical events tied to any calendar date, each entry carrying the year,

Historical events lookup: pass any month and day and get back a list of notable things that happened on that date acro

On-this-day API: notable historical events for any month/day — year, one-line description, and related article links.

This day in history API: notable events that happened on any month/day — the year, a one-line description, and links t

Returns sunrise, sunset, solar noon, and evening golden-hour timing for any latitude/longitude and date, computed dire

Computes the current moon phase name and illumination percentage for any date and location, alongside sunrise, sunset,

Sunrise and sunset API: sun times (sunrise, sunset, solar noon, golden hour) plus moon phase and illumination for any

Sun & moon API: sunrise, sunset, solar noon, evening golden hour, moon phase name, and moon illumination fraction for

Pulls the current day's featured astronomy image along with its title and full explanatory caption, as structured JSON

Today's featured space image — title, high-resolution image URL, and a full written explanation from an astronomer — r

Astronomy photo of the day API: today's featured space image with title, high-res URL, and the full astronomer-written