the402 x402 endpoint directory

Compute Flesch-Kincaid Grade Level, Flesch Reading Ease, Gunning Fog Index, and Automated Readability Index from text.

Calculate the precise difference between two datetimes in years, months, days, hours, minutes, seconds, and total mill

Look up the current Total Value Locked (TVL) for a DeFi protocol via DeFiLlama's public API. Identify the protocol by

Return the current USD spot price for an ERC-20 token, identified by its contract address and network. Sourced from Al

Simulate how a color appears to viewers with protanopia (red-blind), deuteranopia (green-blind), or tritanopia (blue-b

Present and future value of a level annuity (equal periodic payments). Supports an ordinary annuity (payments at perio

Compute the internal rate of return (IRR) of a cashflow stream — the discount rate at which NPV = 0. Index 0 is treate

Backtest a forecasting method on the input series by holding out the last `testSize` observations, forecasting them, a

Three textbook baseline forecasts: mean (forecast = average of history), naive (forecast = last value), drift (linear

Pearson correlation coefficient between two equal-length numeric series. Returns r (the correlation, -1 to 1), r² (var

Enumerate every <a href> in an HTML string with its anchor text and rel attribute. Optionally resolves relative hrefs

Compute the WCAG 2.x contrast ratio between two colors (hex #rgb or #rrggbb) and whether it passes AA/AAA for normal a

Generate a deterministic name-based UUID (version 5, SHA-1) from a namespace + name — the same inputs always yield the

Split text into overlapping chunks for RAG ingestion — by characters (default) or by exact LLM tokens. Returns the chu

Resolve an RFC 6901 JSON Pointer (e.g. /items/0/name) against a JSON value. Returns the value or found:false.

Format a timestamp as a human relative phrase ("3 hours ago", "in 2 days") versus now or a reference time.

Percentage helper. op: "of" (a% of b), "change" (% change a→b), "ratio" (a is what % of b).

Convert an integer between number bases (radix 2-36), e.g. binary↔hex↔decimal. Arbitrary size via BigInt.

Levenshtein edit distance between two strings, plus a 0-1 similarity ratio.

Count characters, words, lines, and (optionally) occurrences of a substring in text.

CRC-32 checksum of a text string (hex), the IEEE polynomial used by zip/png/gzip.

Validate an IBAN: country code, length, and the ISO 13616 mod-97 checksum.

Heuristic user-agent string parser: browser, version, OS, device class, and bot detection.

Validate, pretty-print, or minify JSON. Returns parse errors with position when invalid.

Base64 encode or decode text. mode: encode (default) or decode. Handles URL-safe base64 on decode.

Tamper-evident history of every change to a namespace — an append-only, hash-chained audit log the server attests to (

Atomically increment (or decrement) a numeric key and return the new value — a coordination primitive for counters, lo

Check whether a year is a leap year and get related info: days in that year, the next and previous leap years, and the

Compute multiple similarity metrics between two strings at once: Dice coefficient, Jaccard index, overlap coefficient

Compare two strings in constant time using node:crypto timingSafeEqual, preventing timing side-channel attacks. Return

Convert text to the NATO phonetic alphabet (Alpha, Bravo, Charlie...) or decode phonetic words back to text. Letters a

Validate CSV structure: consistent column counts across rows, properly closed quotes, delimiter detection. Returns row

Count business days (weekdays) between two dates, optionally excluding US federal holidays (MLK, Presidents Day, Memor

Convert a datetime from one IANA timezone to another. Accepts ISO 8601, Unix timestamps (seconds or milliseconds), or

Live spot price (and optional 24-hour change) for one or more coins from CoinGecko's public Simple Price endpoint. Ide

Resolve an ERC-20 contract address to its on-chain metadata: symbol, decimals, name, and logo URL where available. Use

Convert a color between every common notation (hex, rgb, hsl, oklch) at once, plus return the nearest CSS named color.

Risk-adjusted return: (mean return - risk-free rate) / sample standard deviation of returns (n-1). Pass periodsPerYear

Compute the net present value of a stream of cashflows at a given discount rate. Index 0 is treated as t=0 (today, not

Holt-Winters triple exponential smoothing — level + trend + seasonal component. Use for series with a repeating cycle

Flag outliers in a numeric series using either the IQR rule (Tukey fences at 1.5·IQR — robust, default) or z-score (|z

Compute the full descriptive-stats panel for an array of numbers in one call: count, sum, mean, median, mode, stddev (

Decompress a base64-encoded gzip payload. Returns the result as utf8 (text) or base64 (binary). Refuses to expand past

Strip all HTML tags and return plain text. Preserves block-level structure (paragraphs and headings become newline-sep

Great-circle distance between two latitude/longitude points using the haversine formula. Returns kilometers and miles.

Mint a signed JSON Web Token (HMAC: HS256 default, HS384, HS512) from a payload + secret. Pairs with jwt-decode/jwt-ve

Count exact LLM tokens for a string using the real OpenAI BPE (o200k_base for gpt-4o/o-series, cl100k_base for gpt-4/g

Score a password's strength: character-set size, entropy bits, a 0–4 rating, and an estimated offline crack time. The

Compute a precise age (years, months, days) from a birth date to today (or a given date), plus total days.

Convert a value between units of length, mass, temperature, volume, area, speed, time, data, pressure, energy, power,