Calculate a person's exact age in calendar years, months and days from their date of birth, plus total days lived. Reference date defaults to today (UTC). Use this when an agent needs to exact age in years, months and days.

Calculate Body Mass Index from weight (kg) and height (cm), with the WHO weight category and the healthy BMI weight range for your height. Use this when an agent needs to body Mass Index with WHO category.

Project the future value of a deposit with compound interest: choose annual, semi-annual, quarterly, monthly, weekly or daily compounding and see total interest earned. Use this when an agent needs to future value with any compounding frequency.

Count the total days between two dates, plus the breakdown in weeks and days and in calendar years, months and days. Use this when an agent needs to days, weeks and calendar time between two dates.

Calculate the final sale price and the amount saved for any price and percent-off discount, with the working shown. Use this when an agent needs to sale price and savings from a percent off.

Calculate the liters of fuel a trip needs and its total cost from distance, consumption (L/100 km) and price per liter — with optional cost splitting between passengers. Use this when an agent needs to trip fuel and cost, splitable between people.

Calculate the fixed monthly payment for a loan from its principal, annual interest rate and term in years, plus total repaid and total interest (annuity formula). Use this when an agent needs to monthly payment, total cost and interest for any loan.

Calculate X% of Y, what percent X is of Y, and the percent change between two values — with step-by-step working shown. Use this when an agent needs to percent of a number, ratios and percent change.

Estimate reading time from a word count at any reading speed. Defaults to 200 words per minute — the typical silent-reading speed for adults. Use this when an agent needs to how long a text takes to read, by word count.

Calculate the tip for any bill, the grand total, and how much each person pays when splitting. Defaults to a 15% tip. Use this when an agent needs to tip amount, total and per-person split.

Add VAT to a net amount or remove VAT from a gross amount. Standard VAT rates for 36 countries are built in, or override with any custom rate. Use this when an agent needs to add or remove VAT at standard rates for 36 countries.

Convert area units: square millimeters, centimeters, meters and kilometers, hectares, acres, square feet and square miles. Use this when an agent needs to square meters, feet, acres, hectares.

Convert digital storage units: bits, bytes, KB, MB, GB, TB (decimal, ×1000) and KiB, MiB, GiB, TiB (binary, ×1024) — both systems side by side. Use this when an agent needs to decimal (KB/MB/GB) and binary (KiB/MiB/GiB) units.

Convert between metric and imperial length units: kilometers, meters, centimeters, millimeters, micrometers, nanometers, miles, yards, feet, inches and nautical miles. Use this when an agent needs to metric and imperial distance units, instantly.

Convert numbers to Roman numerals (1–3999) and Roman numerals back to numbers, with strict validation that rejects non-standard forms like IIIM or VX. Use this when an agent needs to numbers ↔ Roman numerals, with validation.

Convert speed units: kilometers per hour, miles per hour, meters per second, knots and feet per second with exact definitions. Use this when an agent needs to km/h, mph, m/s, knots and ft/s.

Convert between Celsius, Fahrenheit and Kelvin with exact formulas, reference points (freezing and boiling water) and step-by-step working. Use this when an agent needs to celsius, Fahrenheit and Kelvin, both ways.

Convert Unix epoch timestamps to ISO/UTC dates and back. Millisecond timestamps are detected automatically; invalid dates are rejected with clear errors. Use this when an agent needs to epoch seconds ↔ human dates, both directions.

Convert cooking and liquid volume units: milliliters, liters, cubic meters, US gallons, quarts, pints, cups, fluid ounces, tablespoons and teaspoons. Use this when an agent needs to liters, gallons, cups, milliliters.

Convert between weight and mass units: metric tons, kilograms, grams, milligrams, pounds, ounces and stones with exact international definitions. Use this when an agent needs to kilograms, pounds, ounces and more.

Calculate a transaction's gas fee: gas units × gas price (gwei) gives the ETH cost, multiplied by the ETH price for USD. Exact BigInt math for the wei amounts. Use this when an agent needs to transaction cost in ETH and USD from gas × gwei.

Scan newly created DEX pools on Solana, Base, Ethereum, BSC, Arbitrum or Polygon, filtered by minimum liquidity and maximum age. Each pool comes with liquidity (USD), 24h volume, FDV, buy/sell counts and automatic risk flags (too fresh, thin liquidity, sell pressure). Powered by GeckoTerminal's public API. Use this when an agent needs to fresh DEX launches with liquidity, volume and risk flags.

Live cryptocurrency prices from CoinGecko's public API: current price in USD/EUR/GBP/JPY plus 24-hour change for any coin by id or common ticker (btc, eth, sol…). Cached 60 seconds. Use this when an agent needs to live token prices and 24h change via CoinGecko.

Generate cryptographically secure randomness: passwords with charset rules, hex keys of any byte length, and uniform random integers (rejection sampling, no modulo bias). Never use Math.random for secrets. Use this when an agent needs to cSPRNG passwords, hex keys and uniform integers.

Explain what an EVM transaction would actually do: decodes the calldata (ERC-20 transfers/approvals via known ABIs, unknown selectors via the 4byte directory) and simulates the call against live chain state to report the outcome — including unlimited-approval warnings — without sending anything. Use this when an agent needs to decode and simulate a transaction — before signing it.

One-call on-chain profile of any Ethereum or Base wallet via Blockscout: native balance, transaction and transfer counts, activity recency, top token holdings, and most frequent recent counterparties — with fresh-wallet and high-volume flags. The 'who is this address?' conclusion, not raw RPC data. Use this when an agent needs to on-chain wallet profile: balance, activity, tokens, counterparties.

Convert between wei, kwei, mwei, gwei, microether, milliether and ether with exact BigInt arithmetic. Decimal strings of any magnitude convert without floating-point error. Use this when an agent needs to exact Ethereum unit conversion — no float errors.

Look up any US telephone area code to find the state or territory it serves, or list every area code in a given state. Covers all 404 NANP codes in use, including overlays. Use this when an agent needs to all 404 NANP area codes → state lookup.

Reference database of all 250 countries and territories: ISO 3166-1 codes, capitals, regions, population, area, currencies, languages, TLDs and calling codes. Look up a single country or list by region. Use this when an agent needs to 250 countries: codes, capitals, currencies, populations.

Probe a GET endpoint several times and report status codes and latency statistics (min/avg/max). The cheap way for an agent to verify an API — for example one found on the x402 Bazaar — responds before spending real money calling it. Use this when an agent needs to status and latency stats — test an API before relying on it.

Query the Internet Archive's Wayback index for any URL: when it was first archived, the most recent snapshot, how many years it spans, and recent capture dates. Useful for fact-checking page history, finding deleted content and due-diligence. Use this when an agent needs to how the Internet Archive remembers a URL.

Encode text to base64 or decode base64 back to text. Full UTF-8 support including emoji and non-Latin scripts. Use this when an agent needs to uTF-8 safe base64 in both directions.

Convert text between nine letter cases: UPPER, lower, Title, Sentence, camelCase, PascalCase, snake_case, kebab-case and CONSTANT_CASE. camelCase boundaries are split automatically. Use this when an agent needs to camelCase, snake_case, kebab-case and more.

Turn a cron expression into plain English, validate it, and compute the exact next execution times. Deterministic — the answer to 'when does this cron actually fire?' without guessing. Use this when an agent needs to explain a cron expression and compute the next runs.

Compare two texts line by line using an LCS diff: exact additions, removals and context — in unified-diff style. Deterministic, unlike asking a model to 'find the differences'. Use this when an agent needs to exact line-level diff with unified-style output.

Describe what you need and get back matching x402-paid APIs: our own catalog (54 tools) plus, optionally, the live x402 Bazaar of third-party sellers. The agent's meta-tool — instead of knowing an API exists, ask for the capability. Use this when an agent needs to "I need a tool that does X" → matched paid APIs.

Check whether a domain name is registered or available, via the official RDAP registry protocol (404 = available). For registered domains it also returns the registrar and creation/expiration dates — useful when an agent needs to name a product or verify how long a business has existed. Use this when an agent needs to is this domain taken? Registry answer, not a landing page.

Validate an email address in two layers: strict RFC-style syntax, then a live DNS MX lookup on the domain to confirm the recipient actually runs mail servers. Catches the typos and fake domains that pure regex misses. Use this when an agent needs to syntax + live MX check — can this address receive mail?.

Fetch an RSS or Atom feed and return normalized JSON items: title, link, publication date (ISO) and summary. Server-side fetching with SSRF guard; handles both RSS 2.0 and Atom dialects. Use this when an agent needs to any feed → clean JSON items, no XML parsing on your side.

Compute exact hash digests of UTF-8 text using Web Crypto (SHA family) and a verified pure-JS MD5 for legacy checksums. Deterministic — identical input always yields the identical digest. Use this when an agent needs to sHA-256 / SHA-512 / SHA-1 / MD5, exact digests.

Reference database of HTTP response status codes with phrase, category and explanation. Look up a specific code or list a whole category (1xx–5xx). Use this when an agent needs to look up any HTTP status code's meaning.

Parse iCalendar (.ics) content — meeting invites, conference calendars, exports from Google/Outlook — into structured event JSON: title, start/end, location, organizer and description. Use this when an agent needs to turn .ics calendar files into clean event JSON.

Validate JSON with precise error messages, pretty-print it with any indent, and inspect its top-level type and element counts. Use this when an agent needs to validate, pretty-print and inspect JSON.

Decode a JSON Web Token's header and payload to readable JSON. Pure decoding: signatures are NOT verified and no secret is needed. Claims like exp and iat are rendered as dates. Use this when an agent needs to decode header and payload — no verification.

Calculate the API cost of an LLM call: input and output tokens × published per-million prices for 15 current models (OpenAI, Anthropic, Google, DeepSeek, xAI, Meta). Batch multiplier included for monthly estimates. Use this when an agent needs to tokens × current per-model prices = USD.

Look up MIME content types by type substring or file extension, or list a category — covering text, application, image, audio, video, font and multipart types used in web APIs. Use this when an agent needs to content-Type lookup by type or file extension.

Parse natural-language date and time expressions — "in two weeks", "next friday at 3pm", "dec 25th" — into exact ISO 8601 dates. Deterministic parsing (no LLM guessing); relative expressions resolve against a reference moment you control. Use this when an agent needs to "next friday 3pm" → exact ISO dates.

Convert integers between any bases from 2 to 36 — binary, octal, decimal, hexadecimal and beyond — with BigInt precision (no limit on magnitude). Use this when an agent needs to binary, octal, decimal, hex — any base 2–36.

Verify a claim about a web page's content: fetches the page (SSRF-guarded) and reports whether the expected text appears, with the surrounding excerpt as evidence. The deterministic way for an agent to confirm 'the site says X' before acting on it. Use this when an agent needs to does this page actually say that? Checked, not guessed.

Fetch a PDF (by URL, SSRF-guarded) or accept it as base64 and extract all readable text with page count. Deterministic parsing — no language model, so nothing is invented. Text-based PDFs only; scanned images need OCR (not included). Use this when an agent needs to extract readable text from any PDF — agents can't read PDFs.