Developer Tool

Kenya: VAT standard rate — gazette-cited JSON with last_confirmed and stale.

Supported central bank codes (FED, ECB, BOJ, etc.).

Status of every Ethereum Improvement Proposal as JSON: number, title, status (living, final, last-call, review, draft, stagnant, withdrawn) and link, plus counts by stat…

Convert an integer between numeral bases 2–36 (binary, octal, hex, base36, …). Arbitrary size via BigInt; digits are case-insensitive and a leading minus is allowed.

Convert between integers (1–3999) and Roman numerals in either direction — a digit string is encoded to Roman, a Roman numeral is decoded to an integer. Non-canonical nu…

Split an amount into parts using integer minor-unit math so the shares always sum back to the exact original — no rounding drift. Pass parts for an even split, or ratios…

US Treasury average interest rates on a specific date (YYYY-MM-DD)

Readability metrics: Flesch-Kincaid, word counts

EU VIES VAT number validation

Mexico: Banxico overnight target rate — gazette-cited JSON with last_confirmed and stale.

Fiji: RBF Overnight Policy Rate (OPR) — gazette-cited JSON with last_confirmed and stale.

Verify a claim against 2-4 source URLs: cited passages, cross-source agreement, verdict: consistent | conflicting | insufficient_evidence. Evidence, not truth. Use when…

Fetch Python package metadata from PyPI: version, dependencies, Python compatibility, release history, license.

All WNBA teams with ID, city, abbreviation, and conference. Use team IDs to query schedules and standings.

Current MLB standings — wins, losses, win percentage, games back, home/away splits, and streak. Filter by leagueId: 103 for American League, 104 for National League.

Get one Hacker News or Lemmy thread: the post with its text and the comments flattened with depth and score. One community thread by id from /v1/social/search (hn:<id> o…

Get a short news briefing on a topic where each point cites its numbered source. Send a topic and receive a sourced news briefing in one call: fresh headlines are collec…

Check a dated figure you are about to act on against the publisher's own series, and receive verified, stale, contradicted or unknown with the as-of date. Call it before…

Future value of a present sum and/or a level annuity, given a per-period rate and number of periods. Set dueAtBeginning=true for an annuity-due (payments at the start of…

Compute the level monthly payment, total paid and total interest of a fully-amortizing loan. Handles a 0% rate. Set schedule=true to also return the full month-by-month…

Render GitHub-Flavored Markdown to HTML. Output is sanitized by default (scripts, event handlers and javascript: URLs removed); set sanitize=false to keep raw HTML.

Test whether a version satisfies a semver range (^, ~, x-ranges, ||, hyphen).

Binomial coefficient nCr = n!/(r!(n-r)!), the number of unordered r-subsets of n. Requires r ≤ n and min(r, n-r) ≤ 10000.

Korean business days: the date N business days after (or before) a date, skipping weekends and official Korean public holidays including substitute and temporary holiday…