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Simulator
NewInteractive concurrency problems for Java developers. Deadlock, race conditions, thread starvation — visualized step by step with code and interview prep.
Architect
NewSystem design patterns in motion. Rate limiting, load balancing, caching — see how large-scale systems work with interview prep built in.
All Tools
Format & Validate
Encode & Decode
Base64
Encode and decode Base64 strings with full Unicode support and byte size tracking.
URL Encode / Decode
Encode and decode URL components. Handles special characters, spaces, and Unicode.
JWT Decoder
Decode and inspect JWT tokens — view header, payload, and expiry at a glance.
Hash Generator
Generate MD5, SHA-1, SHA-256, SHA-384, and SHA-512 hashes from text or any file.
Generate
Convert & Tools
Regex Tester
Build and test regular expressions with real-time match highlighting and group capture.
Text Diff
Compare two texts with GitHub-style line and word-level diff highlighting. Context-aware.
JSON ↔ CSV
Convert JSON arrays to CSV and CSV back to JSON. Handles quoted fields and nested values.
Timestamp Converter
Convert between Unix timestamps and human-readable dates. Supports seconds and milliseconds.
Color Picker
Pick colors and instantly convert between HEX, RGB, and HSL with CSS-ready output.
Markdown Preview
Write Markdown with live rendered preview. Split, editor-only, or preview-only modes.
SQLite Viewer
Query SQLite databases in your browser. Full SQL editor with autocomplete, schema explorer, and CSV/JSON export. Nothing leaves your machine.