Developer Tools

Speed up your daily workflow with 18 free developer utilities for encoding, formatting, parsing, generating, and testing common data formats.

From prettifying JSON and decoding JWTs to generating UUIDs, bcrypt hashes, and regex patterns — everything runs entirely in your browser. No scripts, no installs, no data sent to any server.

Encoding & Decoding
Base64 Encoder / Decoder
Encode any text or file to Base64 and decode Base64 strings back to plain text or binary. Supports URL-safe variant.
Use Base64
URL Encoder / Decoder
Encode special characters for safe use in URLs, or decode percent-encoded URL strings back to plain text instantly.
Use URL Encoder
HTML Entities
Encode HTML special characters into entities (&, <, >) or decode them back to plain text for safe output.
Use HTML Entities
Number Base Converter
Convert numbers between binary, octal, decimal, and hexadecimal bases with full step-by-step conversion output.
Use Base Converter
Formatting & Parsing
JSON Formatter
Validate, format, and minify JSON. Prettify messy JSON with syntax highlighting and detailed error detection.
Use JSON Formatter
JSON Unescape & Cleaner
Remove backslashes and clean escaped JSON. Handles stringified, double-escaped, and HTML-entity-encoded JSON.
Use JSON Unescape
JSON Diff
Compare two JSON documents side by side. Highlights added, removed, and changed values with structural diff.
Use JSON Diff
JWT Decoder
Decode and inspect JWT tokens. View header, payload, and signature claims without needing the secret key.
Use JWT Decoder
Regex Tester
Write and test regular expressions with live match highlighting, group capture display, and full flag support.
Use Regex Tester
Timestamp Converter
Convert Unix timestamps to human-readable dates and back. Supports UTC and local timezones.
Use Timestamp Converter
Cron Explainer
Paste any cron expression and get a plain-English description of when it runs, plus the next execution times.
Use Cron Explainer
Color Converter
Convert colours between HEX, RGB, RGBA, HSL, HSLA, and HSV formats with a live colour preview swatch.
Use Color Converter
REST API Checker
Send HTTP requests (GET, POST, PUT, DELETE) with custom headers and body. Inspect response status, headers, and body.
Use REST API Checker
Security & Generation
Password Generator
Generate strong, cryptographically random passwords with customisable length, character sets, and complexity rules.
Use Password Generator
UUID Generator
Generate cryptographically random UUID v4 identifiers. Bulk-generate UUIDs and copy them with one click.
Use UUID Generator
Hash Generator
Generate MD5, SHA-1, SHA-256, and SHA-512 hashes for any input text. Useful for integrity checks and fingerprinting.
Use Hash Generator
Bcrypt Generator
Hash passwords using bcrypt with configurable cost factors. Verify any bcrypt hash against a plain-text password.
Use Bcrypt Generator
Random String Generator
Generate random strings of any length using letters, numbers, symbols, or a fully custom character set.
Use Random String

Free Online Developer Tools

Our developer tools collection helps programmers work faster: encode/decode Base64, URLs, and HTML entities; format and validate JSON; diff JSON documents; decode JWTs; test regular expressions; convert Unix timestamps and number bases; explain cron schedules; convert colours; check REST APIs; and generate passwords, UUIDs, hashes, bcrypt hashes, and random strings — all free, in-browser, no login required.

From the Blog

In-depth technical articles and guides.

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Developer Jun 10, 2026
Production Scheduled Jobs: Idempotency, Monitoring, and Modern Alternatives to Cron
Cron jobs fail silently and traditional cron has no alerting, no history, and no overlap prevention. Here's idempotency design for scheduled jobs, modern alternatives (Celery Beat, AWS EventBridge, Kubernetes CronJobs), and the dead man's switch monitoring pattern.
Developer Jun 7, 2026
Why "P@ssw0rd1" Still Gets Cracked: What Password Strength Actually Means
Most passwords that "pass" complexity rules are still cracked in minutes. Here's how attackers actually work, what password entropy means, and why random generation beats human-chosen passwords every time.
Developer Jun 11, 2026
How Email Attachments Work: MIME Encoding, Base64, and Why Binary Files Need Encoding
Email attachments work because MIME uses Base64 to encode binary files as ASCII text — a system designed in 1992 when email could only carry 7-bit ASCII. Here's how MIME multipart email works, why binary needs encoding, the 33% Base64 overhead on attachment sizes, and how the same system handles HTML form file uploads.
Developer Jun 7, 2026
Negative Numbers, Overflow, and What Hex Reveals About Your Data
Most developers can convert hex to decimal — but two's complement, signed overflow, and bit-width boundaries are where base conversion becomes genuinely useful for debugging real problems.
Developer Jun 9, 2026
Password Managers: How Zero-Knowledge Encryption Works and Which One to Choose
Credential stuffing is the main threat, and unique passwords are the defence — but only a password manager makes that practical at scale. Here's how zero-knowledge encryption works, Bitwarden vs 1Password vs KeePass compared, and how to set up recovery.
Developer Jun 13, 2026
URL Design as API Design: REST Conventions, Versioning Strategies, and the Long-Term Cost of Changing URLs
REST URL conventions, API versioning strategies (URL path vs header vs date-based like Stripe), trailing slash canonicalization, URL length limits, and the link rot problem — URL design decisions made at launch determine API maintainability for years.
Developer Jun 7, 2026
HTML Entities — Encode & Decode Special Characters for Correct, Safe HTML
Learn what HTML entities are, why they exist, the most common named entities, how numeric entities work for any Unicode character, and when modern UTF-8 pages don't need them — with a free HTML entities tool.
Developer Jun 14, 2026
Named Capture Groups, Lookahead, and Lookbehind: Modern Regex Features That Make Patterns Readable
Named capture groups turn regex matches from numbered tuples into readable dictionaries. Lookahead and lookbehind assertions match positions without consuming characters. Here's the modern regex feature set — named groups, non-capturing groups, all four assertion types — with practical patterns for log parsing and URL extraction.
Developer Jun 12, 2026
Practical JSON Diff Workflows: Debugging APIs, Finding Config Drift, and Verifying Migrations
The most common reason to reach for a JSON diff tool is "something changed and I need to know exactly what, fast." Here's four practical workflows: diagnosing API response changes, finding configuration drift between environments, verifying data migrations changed only what was intended, and triaging failing test assertions where the actual difference is buried in a large JSON structure.
Developer Jun 6, 2026
HTML Entities — Encode & Decode Special Characters Correctly
Learn what HTML entities are, which characters always need encoding, how to use <, &,  , and special symbols correctly — with a free HTML entities encoder/decoder tool.