Small tools, done properly.
Every tool runs locally in your browser: nothing you enter leaves the page, and the browser enforces it. The same tools are also available as an HTTP API and an MCP server, which run on the server.
Encoding
URL Encode / Decode
Percent-encode or decode text for URLs, query strings, and form bodies.
/api/url/encode · /api/url/decodeBase64
Encode or decode Base64, standard or URL-safe, with proper UTF-8 handling.
/api/base64/encode · /api/base64/decodeHTML Entities
Escape text for HTML, or decode every named and numeric entity.
/api/html/encode · /api/html/decodeHex
Text to UTF-8 bytes in hex and back: plain, spaced, \x, or 0x.
/api/hex/encode · /api/hex/decodePunycode / IDN
Convert internationalised domain names to xn-- form and back.
/api/punycode/encode · /api/punycode/decodeHashing
Keys & Certificates
Fingerprints
SSH, X.509, SPKI-pin and OpenPGP fingerprints, cross-referenced between formats.
/api/fingerprintCertificate Decoder
Decode certificates, chains and CSRs: names, validity, extensions, chain order.
/api/cert/decodeTLS Checker
Connect to a host and check its certificate chain, trust, host name and protocol (server-side).
/api/tls/checkKey Pair Generator
RSA, ECDSA, Ed25519 and X25519 keys as PEM and OpenSSH, with CSRs and self-signed certs.
Inspect & Identify
JWT Inspector
Decode a JWT, check expiry and algorithm, and verify the signature with a public key or JWKS.
/api/jwt/decodeURL Parser
Split a URL into host, port, path segments and ordered query parameters, exactly as browsers do.
/api/url/parseUUID Generator & Inspector
Generate v4 or time-ordered v7 UUIDs, or decode any UUID’s version, variant and timestamp.
/api/uuid/generate · /api/uuid/inspectText & Data
Text Inspector
Exact character, byte, word and line counts; find letters; reveal invisible and look-alike characters.
/api/text/inspectText Diff
Compare two texts by line, word or character and get a unified diff.
/api/diffJSON Format & Validate
Validate JSON with exact error locations, pretty-print or minify it, sort keys, and find duplicate keys.
/api/json/format · /api/json/lintJSON Schema Validator
Validate JSON against a JSON Schema (2020-12, 2019-09, 7, 4) with every error as a JSON Pointer.
/api/json/schema/validateYAML Format & Validate
Convert between JSON and YAML 1.2, with warnings for YAML 1.1 pitfalls like yes/no and 0755.
/api/convert/json-to-yaml · /api/convert/yaml-to-json · /api/yaml/formatJMESPath Query
Filter, project and reshape JSON with JMESPath expressions, with error positions.
/api/json/queryTOML Format & Validate
Validate, lint and format TOML 1.0 with exact error locations; explore it as a tree; convert to and from JSON.
/api/toml/format · /api/convert/toml-to-json · /api/convert/json-to-tomlCSV Validate & Format
Validate CSV with exact error positions, detect the delimiter and header, infer column types, and reformat or convert to and from JSON.
/api/csv/format · /api/convert/csv-to-json · /api/convert/json-to-csvTime & Scheduling
Time & Time Zones
Current time in any zone; convert ISO 8601, RFC 2822, HTTP dates and Unix timestamps; DST-aware differences and date arithmetic.
/api/time/now · /api/time/convert · /api/time/diff · /api/time/addCron Explainer
Cron expressions in plain English, field by field, with the next run times in your time zone.
/api/cron/explain