the402 x402 endpoint directory

Equation solver for linear equations, quadratics with real or complex roots, and 2x2 systems of linear equations, give

Solves quadratic equations (ax squared + bx + c = 0) from numeric coefficients, returning both roots — real or complex

Equation solver API: exact roots of linear and quadratic equations (real and complex) and 2-variable linear systems, f

Equation solver API: solve linear (ax+b=0), quadratic (ax²+bx+c=0, with real OR complex roots and the discriminant), a

Cryptographic random number draw with a revealed server seed for after-the-fact verification: combine it with your own

Draws a random integer within any min-max range using HMAC-SHA256 over a client-supplied seed, revealing the server se

Random number API with proof: an integer in your range plus the HMAC-SHA256 server seed revealed so the draw is verifi

Provably-fair random number API: an integer in your min-max range drawn via HMAC-SHA256 over your client seed, with th

Physics conversion tool linking light wavelength, frequency, and photon energy — supply any one of nanometers, hertz,

Converts electromagnetic wavelength in nanometers to photon energy in joules and electron-volts, and back, using exact

Wave physics API: convert between light wavelength (nm), frequency (Hz), and photon energy (joules and eV). Uses exact

Photon energy API: convert between electromagnetic wavelength (nm), frequency (Hz), and photon energy (joules and elec

Percentile and outlier calculator: submit a numeric array and get p25, p50, p75, p90, p99 cutoffs plus IQR-based outli

Descriptive statistics calculator returning mean, median, mode, standard deviation, and full percentile breakdown (p25

Statistical summary calculator for a list of up to 100,000 numbers: standard deviation, variance, mean, median, mode,

Statistics API: mean, median, mode, standard deviation, variance, percentiles (p25-p99), range, sum, and IQR outliers

Descriptive statistics API: feed up to 100,000 numbers and get count, sum, mean, median, mode, sample standard deviati

Linear algebra operations on numeric matrices: multiply, add, transpose, invert, or find determinants and eigenvalues

Matrix math calculator for determinant, inverse, transpose, eigenvalues, and matrix multiplication or addition, on arr

Matrix math API: determinant, inverse, transpose, eigenvalues, multiplication, and addition for matrices up to 50x50 —

Least-squares linear fit calculator: pass paired numeric data and get back the best-fit line equation, slope, intercep

Fits a straight trend line through a set of x/y data pairs and returns slope, y-intercept, and R-squared fit quality.

Linear regression API: slope, intercept, R-squared, and the equation of the best-fit line through your x/y data points

Linear regression API: fit a least-squares line through paired x/y data and get slope, intercept, R-squared goodness-o

Turns structured JSON arrays into spreadsheet-ready CSV, up to 10,000 rows, headers unified across objects, nested fie

Converts an array of JSON objects, up to 10,000 rows, into a properly escaped CSV file with a unified header row, hand

JSON to CSV converter API: turn an array of JSON objects (up to 10,000 rows) into a properly escaped CSV with a unifie

Website health probe: checks whether any URL is currently reachable and returns its response time, content type, and c

Website uptime check API: status code, response time in ms, and key headers for any URL in one call. The heartbeat pro

HTTP check API: probe any URL and get its status code, response time in milliseconds, server header, content type, and

Solid geometry calculator returning exact volume and surface area for spheres, cylinders, cones, cubes, and rectangula

Shape math calculator for area, perimeter, and diagonal length of circles, rectangles, and triangles from plain numeri

Geometry calculator API: area, perimeter, volume, and surface area for circles, rectangles, triangles, spheres, cylind

Geometry API: exact area, perimeter, volume, surface area, and diagonals for circles, rectangles, triangles (Heron's o

Return-on-investment and compound-growth calculator: supply an initial amount, rate, and time horizon to get final val

Loan payment calculator covering compound interest growth, monthly installment amounts, and return-on-investment math

Mortgage and loan payment calculator: enter principal, annual rate, and term to get the exact monthly payment, total a

Financial math API: compound interest with any compounding frequency, monthly loan/mortgage payment and total interest

Financial calculator API: compound interest (final amount, interest earned, effective annual rate), loan/mortgage paym

Semantic vector generation: turns batches of text (up to 64 per request) into dense 768-dimension embeddings ready to

Vector embeddings API: converts up to 64 pieces of text per call into 768-dimensional numeric vectors suitable for sim

Text embeddings API without an API key: up to 64 texts per call, 768-dimension embedding vectors computed on our own h

Embeddings API: 768-dimension embedding vectors for up to 64 texts per call, computed locally on our hardware — no Ope

Periodic table reference returning full physical and chemical data — atomic mass, category, period, group, electron sh

Chemical element reference: look up any of the 118 known elements by atomic number, symbol, or name and get atomic mas

Chemical element API: atomic number, atomic mass, electron shells, electronegativity, and physical properties for any

Periodic table API: full data for any of the 118 elements by symbol, name, or atomic number — atomic mass, category, p

Periodic table API: complete data for any of the 118 chemical elements — look up by symbol (Fe), name (iron), or atomi

Determines the language of any input text with a confidence score and runner-up candidates, useful when a short snippe

Identifies which of 60+ languages a piece of text is written in, returning a confidence score and the top three candid