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UUID generators, JSON formatters, JWT decoders and more — fast, free, and 100% private. Every tool runs locally in your browser; your data never touches a server.
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Popular categories
Encoding
16 toolsThe most-searched category on DevTools Hub — URL encoding, decoding, and Base64 conversions.
JWT
6 toolsThe single biggest source of search traffic — decoding claims, checking expiration, and JWT security.
SQL
4 toolsValidating and formatting SQL syntax across Postgres, MySQL, and more.
Regex
5 toolsTesting and building JavaScript regular expressions without leaving the browser.
Toolkits
Generators Toolkit
3 toolsThree independent generators for the test data every project eventually needs — unique IDs, strong passwords, and placeholder text. All run entirely in your browser.
JSON Toolkit
10 toolsFormat, validate, diff, minify, convert, query, and schema-generate/validate JSON — ten tools for the format everything speaks. All run entirely in your browser.
Encoding Toolkit
16 toolsBase64, URL, HTML, hex, and ASCII encoding and decoding, plus query string and full URL parsing, building, inspection, Unicode analysis, and string-literal escaping — sixteen tools for the encodings that show up constantly in web development. All run entirely in your browser.
Date & Time Toolkit
5 toolsTimestamps, timezones, and cron schedules — five tools for the two date-and-time problems every backend eventually runs into. All run entirely in your browser.
JWT Toolkit
6 toolsEverything for working with JSON Web Tokens, in one place — decode, understand, verify, and build them. All six tools run entirely in your browser; nothing you paste is ever sent anywhere.
Hashing Toolkit
5 toolsMD5, SHA, checksums, and HMAC — five tools for hashing text, verifying files, and signing messages. All run entirely in your browser.
Regex Toolkit
5 toolsBuild, test, visualize, and debug JavaScript regular expressions — five tools covering the whole regex workflow. All run entirely in your browser.
SQL Toolkit
4 toolsFormat, validate, minify SQL, and find the real bottleneck in a query plan — four tools covering readability, correctness, and performance. All run entirely in your browser.
OpenAPI Toolkit
5 toolsView, validate, diff, and put an OpenAPI/Swagger document to work — five tools covering the full spec lifecycle. All run entirely in your browser.
Docker Toolkit
4 toolsValidate, lint, format, and visualize Docker Compose files and Dockerfiles — four tools covering the whole Docker workflow. All run entirely in your browser.
GitHub Actions Toolkit
4 toolsValidate, visualize, lint, and audit secrets in GitHub Actions workflows — four tools covering correctness and security. All run entirely in your browser.
Environment Toolkit
4 toolsValidate, diff, and convert .env files — four tools for the dotenv format's real parsing rules and the gotchas that fail silently. All run entirely in your browser.
Kubernetes Toolkit
4 toolsValidate, format, calculate resources, and diff Kubernetes manifests — four tools covering correctness, readability, and resource planning. All run entirely in your browser.
YAML Toolkit
2 toolsValidate and format YAML — syntax errors, duplicate keys, parser-version gotchas, and consistent indentation — schema-agnostic, for any YAML file. All run entirely in your browser.
Latest tools
JSONPath Generator
Click a key or value in a JSON document to get its JSONPath expression.
JSONPath Tester
Test a JSONPath expression against a JSON document and see every match, live.
JSON Schema Generator
Generate a JSON Schema (Draft-07 or 2020-12) from a sample JSON document.
JSON Schema Validator
Validate JSON data against a JSON Schema (Draft-07 or 2020-12), with every failing rule and its path.
YAML Formatter
Re-indent YAML with a consistent indent size and optional line wrapping, comments preserved.
YAML Validator
Check YAML for syntax errors, duplicate keys, tab indentation, and YAML 1.1/1.2 boolean ambiguity.
Latest articles
View all postsWhat Is a Cron Expression?
A cron expression is the five-field string that tells cron (and Kubernetes, and GitHub Actions) when to run a job. Here's the short definition, where the format comes from, and where you'll run into it.
URL Encoding in Java
Verified: why URLEncoder is a form encoder, not a URI encoder (space becomes +, running it on a whole URL breaks the path), the ~ it escapes that RFC 3986 says it shouldn't, and why java.net.URI is the right tool for building a real URI.
URL Encoding in Python
urllib.parse's split API, verified: why quote() leaves / unescaped by default, quote vs. quote_plus for spaces, the unquote/unquote_plus mismatch that leaves a stray + behind, and the urlencode doseq trap for list values.