Airport lookup in a bundled OurAirports extract (public domain, dated in the answer): by IATA or ICAO code, by name or city words, or the nearest airports within a radius (up to 300 km) of a point. Covers large and medium airports and every airport with an IATA code; small airports without one are left out. Name, codes, type, city, country, coordinates, elevation and Wikipedia link. No time zone (not in the source).

Check whether a Base transaction settled x402 payments (USDC transferWithAuthorization, EIP-3009): for each, the payer, the payTo address, the amount in USDC, the authorization nonce, the facilitator that sent it, and the seller behind the payTo address from Bazaar listings (origins and 30-day payers).

Maps a US-listed stock ticker, SEC CIK number or company name fragment to the other two, with the exchange: an exact ticker or CIK, or up to 10 names matching the words you give (the names that start with it first). From the SEC's company ticker file (public domain), cached a day and trimmed before caching. Covers companies with an SEC ticker only; a name with no match is a 404, not charged.

A Wikipedia page summary by title or search words, in any language: title, short description, summary, page URL, thumbnail and Wikidata ID. For organisations, people and places, Wikidata facts: official website, inception, country, headquarters, date of birth and coordinates. Text is CC BY-SA 4.0 with attribution. Not found returns search suggestions.

Active US National Weather Service alerts for a state or a point: event, severity, urgency, area, onset, end of the event (ends), expiry of this message (expires), headline and instruction (cut to 400 characters). Attribution: National Weather Service, public domain.

MD5, SHA-1, SHA-256, SHA-512, SHA3-256 and Keccak-256 (Ethereum) of a text, or of bytes given as hex or base64, as hex and base64.

Generate random IDs from a cryptographic source: UUID v4, UUID v7 (time ordered), ULID or nanoid, up to 100 at a time.

The URLs a sitemap lists, with last modified dates, or the sitemaps a sitemap index lists. Given a site instead of a sitemap, it finds the sitemap from robots.txt or /sitemap.xml. Gzipped sitemaps are read too.

Decode a JSON Web Token's header and claims, and say when it was issued, when it expires, whether it has expired and in how many seconds it will. The signature is not verified.

Validate a JSON value against a JSON Schema (draft-07 and 2019-09 keywords, formats such as email, uri, date-time) and list every error with its path. Patterns run on RE2, so a schema cannot stall the check.

Check whether a phone number is valid and possible, find its country and type (mobile, fixed line, toll free and others), and format it as E.164, international and national (libphonenumber metadata).

Evaluate an arithmetic expression with 64 significant digits (no floating point surprises): operators, parentheses, powers, roots, logs, trigonometry, percentages, constants, units (5 inch to cm) and simple statistics.

Date and time calculations in pure code. op=diff: calendar years, months and days between two dates, and the total days. op=add or subtract: move a date by years, months, weeks, days, hours or minutes (month ends are clamped). op=info: weekday, ISO week, day of year, quarter, and age from birthDate. op=tz: a local date-time in one IANA time zone shown in another. Impossible dates are a 400 with the reason.

Convert an amount between a crypto and a fiat currency, or between two crypto assets, at the current spot price: the rate, the converted amount, the pair path used (direct, or through USD) and the time of the rate. Spot prices from Coinbase, Kraken as the fallback. A spot rate, not an executable quote: no fees or slippage. Fiat to fiat is refused; use the FX tool for that. Information only, not financial advice.

Encode or decode text as base64, base64url, hex, URL (percent) encoding, HTML entities, punycode (domain names) or quoted-printable. Body { input, scheme, direction }, up to 1 MB. Invalid input to decode is a 400 that names the position of the first bad character. Unknown HTML entities are reported, not guessed. Pure code, no outside request.

Loan and investment calculator in exact cents, no outside source. mode=annuity: monthly payment, total interest and the full amortisation schedule (up to 600 months). mode=compound: future value of an initial sum plus monthly contributions. mode=npv or irr: discount or internal rate of return of a list of cashflows (up to 200, the first at time 0). Rates are percentages from 0 to 100 a year (per period for npv and irr); terms up to 50 years.

Count the tokens of a text for OpenAI models (o200k_base for GPT-4o and later, cl100k_base for GPT-4), with characters, words and lines, to size prompts and estimate cost.

Checks whether a URL's path may be crawled under robots.txt (RFC 9309): the verdict for a user agent (default: *, Googlebot, Bingbot, GPTBot, ClaudeBot, PerplexityBot, Google-Extended and CCBot), the rule that decided it and its line, crawl-delay, sitemaps and the matching group's lines. Longest rule wins, allow wins a tie, * and $ work. No robots.txt means everything is allowed; a server error is a 503, not charged.

TLS certificate expiry for up to 10 hostnames: the issuer, validity dates, days left, all DNS names and a status (ok, expiring within 14 days, expired, none found). Read from Certificate Transparency logs (CertSpotter, crt.sh as fallback), so it is the newest valid certificate issued for each name, not the one the server presents; the answer also says whether https answers and its HSTS header. Public hostnames only.

Use this service before importing or publishing JSON to check it against a restricted draft-07 schema. Send dataJson and schemaJson as JSON-encoded strings. Max 256 KiB UTF-8 each, depth 32; bounded node and work limits. Supports types, required properties, items, enums and numeric/length bounds. No regex, combinators or external references. Invalid business data returns valid=false.