Sindri

Live cryptocurrency price API. Returns the current market price (in USD) of any cryptocurrency by ticker symbol (BTC, ETH, DOGE, etc.) — live market data an LLM cannot know on its own.

URL decoder API. Decodes percent-encoded URL text back to plain text.

MD5 hash generator API. Computes the MD5 hex digest of any text. Deterministic and instant — an LLM cannot reliably compute real cryptographic hashes on its own.

SHA-256 hash generator API. Computes the SHA-256 hex digest of any text. Deterministic and instant — an LLM cannot reliably compute real cryptographic hashes on its own.

Deterministic primality test using the Miller-Rabin algorithm with a witness set proven deterministic for all integers below 3.3x10^24, safely covering the full JavaScript safe-integer range.

Decodes (does not verify) a JWT by base64url-decoding its header and payload segments. Signature validity is never checked — do not use this to authenticate a token.

Loan payment calculator. Computes the fixed monthly payment for a standard amortizing loan and returns the full month-by-month principal/interest/balance schedule — exact amortization math an LLM cannot reliably compute by hand for hundreds of periods.

Matrix operations: multiply, transpose, determinant, and invert, for matrices up to 20x20. Uses the ml-matrix library's LU decomposition (LuDecomposition) for determinant and inversion, with a numerical near-singularity guard beyond the library's exact-singular check.

Lookup of standard physical constants (speed of light, gravitational constant, Planck constant, elementary charge, Avogadro number, Boltzmann constant, gas constant, electron mass) with exact published CODATA values.

Generates a QR code for the given text, returned as a base64-encoded PNG data URL, computed entirely locally with no external service call.

Savings rate calculator. Divides the gap between monthly take-home income and spending by income to produce your personal savings rate as a percentage.

Solves a system of linear equations (Ax = b) using the ml-matrix library's LU decomposition (LuDecomposition), with a near-singularity guard beyond the library's exact-singular check, for systems up to 20x20.

Tesla savings calculator. Compares annual electricity cost for a Tesla against annual gas cost for a comparable gas vehicle, accounting for free-charging usage, and computes break-even years, cost per full charge, and gas-price-equivalent effective MPG.

Unit conversion for length, mass, volume, and temperature using exact conversion factors (temperature uses the correct affine formulas, not simple multiplication).

URL encoder API. Percent-encodes text for safe use in a URL query string or path segment, handling reserved-character rules LLMs often get wrong by hand.

True-random-date generator API. Generates a bounded random date via one of: anytime, past, future, between, betweens, recent, soon, birthdate. between/betweens require "from" and "to" date strings. Accepts optional locale (default en_US). Date args must parse to a valid date with year 1000-9999.

HSA (Health Savings Account) growth calculator. Projects year-by-year account balance from a starting value, annual contributions, annual expense withdrawals, and an annual return rate.

Prime factorization of an integer via trial division, returning the full list of prime factors (with repetition).

Sunrise, sunset, solar noon, day length, and moon phase for a given latitude/longitude/date, computed via the suncalc library (standard solar/lunar position algorithms) — precise astronomical math an LLM cannot reliably compute mentally.

Checksummed-identifier-format generator API. Generates a structurally valid isbn, upc, vin, or imei, each computed with its real check-digit algorithm. vin and imei take no arguments. Accepts optional locale (default en_US).

Compares two semantic version strings and reports which is greater, lesser, or equal, using the standard semver comparison rules.

Descriptive statistics summary (mean, median, variance, standard deviation, and 25th/75th/90th percentiles via linear interpolation, matching R and numpy's default "type=7" method) over a numeric array of up to 10,000 elements.

Windfall impact on FIRE timeline calculator. Runs the FIRE net-worth simulation twice — with and without a one-time lump sum added at a given year — and reports how many years the windfall shaves off your time to financial independence.

Rental property investment calculator. Full multi-year deal analysis for a rental property deal: mortgage, per-category rent/expense growth, a sale scenario, IRR, and cumulative totals over the holding period, alongside the first-year NOI/cap-rate/cash-on-cash snapshot.

Purchase impact on FIRE timeline calculator. Runs the FIRE net-worth simulation twice — with and without a one-time purchase amount deducted at a given year — and reports how many years that purchase delays financial independence, quantifying its true opportunity cost.

Portfolio rebalancing calculator. Given current holdings and target allocation percentages, computes the dollar gap per asset and the monthly buy/sell inflow needed to reach the target allocation over a chosen rebalancing period.

Keeping up with inflation calculator. Computes the pre-tax raise needed under two scenarios — keeping the same dollar amount saved, or maintaining the same savings rate — after inflation raises your spending and a marginal tax rate reduces the raise itself.

Hybrid vs gas savings calculator. Compares annual fuel cost between a hybrid and a conventional gas vehicle based on miles driven, gas price, and each vehicle's MPG, and computes the break-even point for the hybrid's price premium.

Gas mileage savings calculator. Compares annual fuel cost between two gas-powered vehicles based on miles driven, gas price, and each vehicle's MPG, and computes the break-even point for any price premium of the more efficient vehicle.

Electric car savings calculator. Compares annual electricity cost against annual gas cost for a comparable gas vehicle, accounting for free-charging usage, and computes break-even years, cost per full charge, and gas-price-equivalent effective MPG.