Engineering utilities,
reimagined.
Your data never leaves the browser. A privacy-first collection of essential tools for the modern developer workflow.
JSON Formatter
Format, beautify and validate JSON instantly. Real-time syntax validation with detailed error messages.
JWT Decoder
Instant decode and claim verification.
Base64
Fast encode and decode strings.
URL Encoder
RFC 3986 compliant encoding.
Hash Generator
MD5, SHA-1, SHA-256, SHA-512 & more.
Cron Builder
Human-readable cron expressions for any schedule.
Diff Checker
Compare two texts and highlight differences.
UUID Generator
Bulk generate secure UUIDs.
JSON Repair
Fix broken and malformed JSON instantly.
Password Generator
Cryptographically secure random passwords.
Password Checker
Check strength and estimated crack time.
Color Converter
HEX, RGB and HSL with CSS output.
Image to Base64
Data URL, HTML, CSS and Markdown output.
Unix Timestamp
Epoch to date, date to epoch, all formats.
SQL Formatter
MySQL, PostgreSQL, SQLite, T-SQL & more.
HTTP Status Codes
Searchable reference with REST API context.
YAML Validator
Lint YAML with line/column error location.
Case Converter
camelCase, snake_case, kebab-case and more.
Chmod Calculator
Visual Linux file permission calculator.
Base Converter
Binary, octal, decimal, hex — all at once.
XML Formatter
Beautify, validate and minify XML instantly.
JSON Validator
Lint JSON with exact error positions.
JSON to YAML
Turn JSON into readable YAML config.
YAML to JSON
Convert YAML config to formatted JSON.
JSON to CSV
Flatten JSON arrays into spreadsheets.
CSV to JSON
Parse CSV rows into a JSON array.
JSON Tree Viewer
Explore nested JSON as a collapsible tree.
Developer guides
Short, practical explainers that go with the tools.
APIs & security
Data formats
Quick reference
Look up a single cron schedule, permission mode or status code.
One page per common schedule, with next run times and Quartz, AWS and Kubernetes equivalents.
What 755, 644, 600 and other permission modes mean, when to use them and the risks.
Searchable list of every status code, with in-depth pages for the ones APIs use most.
Frequently asked questions
- Is my data safe? Do you store anything I paste or upload?
- No. Every tool on DevEssentials runs entirely in your browser using JavaScript. Nothing you type, paste, or upload is ever sent to a server. There is no backend — your data never leaves your device. That matters more than it sounds: read about the hidden risk of server-side developer tools and the JSONFormatter and CodeBeautify data leak. You can check this yourself in DevTools; about DevEssentials shows how. The details are in our privacy policy.
- Do I need to create an account or sign up?
- No account, no email, no signup. All tools are free and open to use immediately.
- Do the tools work offline?
- Yes. Once the page has loaded, all tools work without an internet connection. There are no API calls to external services.
- Are these tools free to use commercially?
- Yes. You can use DevEssentials for personal or commercial work without restrictions. Use of the site is covered by our terms of use.