A collection of fast, practical web utilities built to simplify everyday data work. From transforming datasets to automating workflows and inspecting files, these tools are designed to help you get results quickly with minimal setup and friction. Focused on in-browser experience using JavaScript and WebAssembly. No server required.

Recently Added

  • KV Store Terminal (Redis-style) — A Redis-style key-value database running entirely in your browser. Strings, lists, hashes, sets, and TTL expiry — driven from a real terminal with a live key browser. Persisted to IndexedDB. No server upload. (Jul 21, 2026)
  • Graphing Calculator — Plot multiple functions on an interactive canvas graph with pan, zoom, and value tracing, plus a built-in scientific calculator. No charting library, no eval() — a hand-written expression parser compiles formulas to JS closures. 100% client-side. (Jul 17, 2026)
  • Web Serial Terminal — Talk to Arduino, ESP32, and other USB/serial devices directly from your browser using the Web Serial API. Full terminal UI, configurable baud rate, hex view, and log export. No drivers, no server upload. Chrome/Edge only. (Jul 16, 2026)
  • Linux in the Browser — Boot a real Linux kernel entirely in your browser tab using v86, an x86 PC emulator compiled to WebAssembly. Drop into a live BusyBox root shell and run commands — no server, no plugin, fully sandboxed. No server upload. (Jul 7, 2026)
  • Postgres Playground (PGlite) — A real PostgreSQL server compiled to WebAssembly, running entirely in your browser. Full SQL — JSONB, window functions, CTEs, arrays — with an in-browser schema browser and optional IndexedDB persistence. No server upload, no external database. (Jul 3, 2026)
  • Multi-Tab Sync Lab — Open in several tabs to see BroadcastChannel presence and chat, live leader election via the Web Locks API, and a hands-on race-condition demo comparing unsafe vs. lock-protected concurrent counter updates. No server upload. (Jul 1, 2026)
  • YAML / TOML / JSON / XML Converter — Convert between YAML, JSON, TOML, and XML in real time — paste any format, get any other. Perfect for Kubernetes configs, pyproject.toml, pom.xml, and more. No server upload. (Jun 26, 2026)
  • JavaScript REPL Terminal — Run JavaScript in a sandboxed Web Worker with a full terminal UI. Top-level await, ESM imports from any CDN, console capture, persistent history, and full line-editing. No install, no backend. (Jun 18, 2026)
  • Network Latency Monitor — Measure real-time round-trip latency to Cloudflare, Google, and jsDelivr CDN endpoints. Charts jitter over time, computes min/avg/max/packet-loss, estimates download speed, and surfaces Network Information API data. No server upload. (Jun 17, 2026)
  • GPS Route Recorder — Record your GPS route live in the browser using the Geolocation API. View your path on a canvas map with real-time distance, speed, and duration. Import existing GPX files to visualize. Export as GPX or CSV. No server upload. (Jun 16, 2026)

Recently Updated

  • KV Store Terminal (Redis-style) — A Redis-style key-value database running entirely in your browser. Strings, lists, hashes, sets, and TTL expiry — driven from a real terminal with a live key browser. Persisted to IndexedDB. No server upload. (Jul 21, 2026)
  • Graphing Calculator — Plot multiple functions on an interactive canvas graph with pan, zoom, and value tracing, plus a built-in scientific calculator. No charting library, no eval() — a hand-written expression parser compiles formulas to JS closures. 100% client-side. (Jul 17, 2026)
  • Web Serial Terminal — Talk to Arduino, ESP32, and other USB/serial devices directly from your browser using the Web Serial API. Full terminal UI, configurable baud rate, hex view, and log export. No drivers, no server upload. Chrome/Edge only. (Jul 16, 2026)
  • Linux in the Browser — Boot a real Linux kernel entirely in your browser tab using v86, an x86 PC emulator compiled to WebAssembly. Drop into a live BusyBox root shell and run commands — no server, no plugin, fully sandboxed. No server upload. (Jul 7, 2026)
  • Postgres Playground (PGlite) — A real PostgreSQL server compiled to WebAssembly, running entirely in your browser. Full SQL — JSONB, window functions, CTEs, arrays — with an in-browser schema browser and optional IndexedDB persistence. No server upload, no external database. (Jul 3, 2026)
  • Multi-Tab Sync Lab — Open in several tabs to see BroadcastChannel presence and chat, live leader election via the Web Locks API, and a hands-on race-condition demo comparing unsafe vs. lock-protected concurrent counter updates. No server upload. (Jul 1, 2026)
  • YAML / TOML / JSON / XML Converter — Convert between YAML, JSON, TOML, and XML in real time — paste any format, get any other. Perfect for Kubernetes configs, pyproject.toml, pom.xml, and more. No server upload. (Jun 26, 2026)
  • JavaScript REPL Terminal — Run JavaScript in a sandboxed Web Worker with a full terminal UI. Top-level await, ESM imports from any CDN, console capture, persistent history, and full line-editing. No install, no backend. (Jun 18, 2026)
  • Network Latency Monitor — Measure real-time round-trip latency to Cloudflare, Google, and jsDelivr CDN endpoints. Charts jitter over time, computes min/avg/max/packet-loss, estimates download speed, and surfaces Network Information API data. No server upload. (Jun 17, 2026)
  • GPS Route Recorder — Record your GPS route live in the browser using the Geolocation API. View your path on a canvas map with real-time distance, speed, and duration. Import existing GPX files to visualize. Export as GPX or CSV. No server upload. (Jun 16, 2026)

Browse by Category

AI (1)

  • WebGPU LLM Chat — Chat with AI models running entirely in your browser using WebGPU. No API keys, no server.

Audio (1)

  • M4A to WAV Converter — Convert M4A audio files to WAV (8kHz, mono, mu-law) in your browser using FFmpeg WASM. No server upload.

Data and time utilities (1)

Databases (6)

  • AI Data Studio ↗ — AI-powered data studio for exploring and analyzing datasets
  • DuckDB (SQL Runner) — Run SQL queries in your browser using DuckDB-WASM. Upload a CSV and query it instantly.
  • KV Store Terminal (Redis-style) — A Redis-style key-value database running entirely in your browser. Strings, lists, hashes, sets, and TTL expiry — driven from a real terminal with a live key browser. Persisted to IndexedDB. No server upload.
  • Postgres Playground (PGlite) — A real PostgreSQL server compiled to WebAssembly, running entirely in your browser. Full SQL — JSONB, window functions, CTEs, arrays — with an in-browser schema browser and optional IndexedDB persistence. No server upload, no external database.
  • SQLime ↗ — Online SQLite playground to run SQL queries in your browser
  • SQLite File Viewer — Open any .sqlite or .db file directly in your browser using SQLite WASM (sql.js). Browse tables, inspect schemas, run SQL queries — no server upload.

Design (2)

  • Excalidraw ↗ — Virtual whiteboard for sketching diagrams
  • WCAG Color Contrast Checker — Check WCAG 2.1 AA/AAA contrast ratios, get an APCA perceptual contrast score, simulate colour blindness (deuteranopia, protanopia, tritanopia), and find accessible colour pairs. Uses the EyeDropper API to pick colours from anywhere on screen. No server upload.

Development (17)

  • Codapi ↗ — Interactive code examples - embed executable code snippets in docs
  • Cron Expression Parser — Decode any cron expression into plain English, see the next 10 scheduled run times, and understand each field at a glance. No server upload.
  • DNS Lookup — Query any DNS record type (A, AAAA, MX, TXT, NS, SOA, CAA) directly from your browser via DNS-over-HTTPS. Auto-detects SPF, DMARC, and DKIM in TXT records. No server upload.
  • HAR Waterfall Analyzer — Drop a .har file from Chrome/Firefox/Safari DevTools to get a professional request waterfall, DNS/TCP/TLS/TTFB timing phases per request, resource type breakdown, and performance insights. No server upload.
  • JavaScript REPL Terminal — Run JavaScript in a sandboxed Web Worker with a full terminal UI. Top-level await, ESM imports from any CDN, console capture, persistent history, and full line-editing. No install, no backend.
  • JWT Decoder — Decode and inspect JSON Web Tokens. Visualises header, payload, expiry status, and timestamp claims. No server upload.
  • Linux in the Browser — Boot a real Linux kernel entirely in your browser tab using v86, an x86 PC emulator compiled to WebAssembly. Drop into a live BusyBox root shell and run commands — no server, no plugin, fully sandboxed. No server upload.
  • Mermaid Diagram Editor — Create flowcharts, sequence diagrams, class diagrams and more with live preview.
  • Multi-Tab Sync Lab — Open in several tabs to see BroadcastChannel presence and chat, live leader election via the Web Locks API, and a hands-on race-condition demo comparing unsafe vs. lock-protected concurrent counter updates. No server upload.
  • Network Latency Monitor — Measure real-time round-trip latency to Cloudflare, Google, and jsDelivr CDN endpoints. Charts jitter over time, computes min/avg/max/packet-loss, estimates download speed, and surfaces Network Information API data. No server upload.
  • React Examples ↗ — Collection of random React tool examples and demos
  • Regex Tester — Test regular expressions with live results
  • SQL Pretty Printer — Format and beautify SQL queries with proper indentation. Supports multiple dialects.
  • Text Diff Viewer — Compare two blocks of text line-by-line with highlighted additions and deletions. No server upload.
  • URL Encoder/Decoder — Encode and decode URL components
  • WebSocket Playground — Connect to any WebSocket server, send and receive messages in real time. JSON auto-formatting with syntax highlighting, binary hex mode, message templates, connection timer, and log export. No server upload.
  • YAML / TOML / JSON / XML Converter — Convert between YAML, JSON, TOML, and XML in real time — paste any format, get any other. Perfect for Kubernetes configs, pyproject.toml, pom.xml, and more. No server upload.

Image and media (2)

IoT (3)

  • MQTT WebSocket Explorer — Connect to any MQTT broker over WebSocket directly from your browser. Subscribe to topics, publish messages, and debug live IoT device streams. Auto-discovers topic trees, pretty-prints JSON payloads, and exports logs. No server upload. Perfect for ESP32, Home Assistant, and IoT dev.
  • Web Bluetooth BLE Explorer — Connect to Bluetooth Low Energy devices wirelessly from your browser. Explore GATT services, read and write characteristics, and stream live sensor data from ESP32, Arduino, health monitors, and custom IoT nodes. No drivers, no app install. Chrome/Edge only.
  • Web Serial Terminal — Talk to Arduino, ESP32, and other USB/serial devices directly from your browser using the Web Serial API. Full terminal UI, configurable baud rate, hex view, and log export. No drivers, no server upload. Chrome/Edge only.

Marketing (1)

  • UTM Tag Generator ↗ — Generate UTM tracking parameters for campaign URLs with QR code generation

Security (4)

  • Encrypt / Decrypt Message — Encrypt a message with a passphrase and share it via URL
  • EXIF Photo Inspector — Inspect hidden metadata inside photos — GPS location, camera model, timestamps, and more. Strip EXIF data for privacy before sharing. Entirely in your browser, no server upload.
  • File Hash Calculator — Compute SHA-256, SHA-512, SHA-384, and SHA-1 hashes of any file in your browser. Drag and drop to verify downloads or check integrity. No server upload.
  • Image Steganography — Hide secret text inside PNG images using LSB (Least Significant Bit) steganography — and extract it again. Optional passphrase protection. No server upload.

SEO (1)

Text and document (5)

  • Base64 Encoder/Decoder — Encode and decode Base64 strings
  • JSON ↔ CSV Converter — Convert between JSON and CSV in your browser. Handles nested objects, quoted fields, and type inference. No server upload.
  • JSON Formatter — Format and validate JSON with syntax highlighting
  • Markdown Preview — Write Markdown and see the rendered HTML live. Supports GFM tables, task lists, and exports to .md or .html.
  • OCR - Extract Text from Images & PDFs — Extract text from images and PDFs directly in your browser using Tesseract.js. No server upload.

Utilities (10)

  • Clipboard Viewer — Read text from your clipboard and inspect it in your browser. No server upload.
  • GPS Route Recorder — Record your GPS route live in the browser using the Geolocation API. View your path on a canvas map with real-time distance, speed, and duration. Import existing GPX files to visualize. Export as GPX or CSV. No server upload.
  • Graphing Calculator — Plot multiple functions on an interactive canvas graph with pan, zoom, and value tracing, plus a built-in scientific calculator. No charting library, no eval() — a hand-written expression parser compiles formulas to JS closures. 100% client-side.
  • QR Code Reader ↗ — Scan QR codes and preview URLs before navigating. No server upload.
  • Reader View Button — Add a reader mode button to any webpage. Strips clutter and presents clean, readable content.
  • Screen Recorder — Record your screen, window, or browser tab with optional system audio and microphone — entirely in the browser. No server upload.
  • Simple RSS Reader ↗ — Read and browse RSS and Atom feeds directly in your browser
  • Site Analytics — Personal browsing analytics stored in your browser
  • Speech Transcription — Transcribe speech to text in real time using your browser's built-in Web Speech API. Timestamped segments, multi-language, export as .txt or .md. No server upload.
  • WebRTC P2P File Transfer — Transfer files directly between two browsers — peer-to-peer via WebRTC DataChannels. No server, no upload, no size limit. Exchange a short offer/answer handshake by copy-paste, then files stream browser-to-browser at full speed.

Video and Media Extractor (1)

Browse All by Month

July 2026 (6)

  • KV Store Terminal (Redis-style) — A Redis-style key-value database running entirely in your browser. Strings, lists, hashes, sets, and TTL expiry — driven from a real terminal with a live key browser. Persisted to IndexedDB. No server upload.
  • Graphing Calculator — Plot multiple functions on an interactive canvas graph with pan, zoom, and value tracing, plus a built-in scientific calculator. No charting library, no eval() — a hand-written expression parser compiles formulas to JS closures. 100% client-side.
  • Web Serial Terminal — Talk to Arduino, ESP32, and other USB/serial devices directly from your browser using the Web Serial API. Full terminal UI, configurable baud rate, hex view, and log export. No drivers, no server upload. Chrome/Edge only.
  • Linux in the Browser — Boot a real Linux kernel entirely in your browser tab using v86, an x86 PC emulator compiled to WebAssembly. Drop into a live BusyBox root shell and run commands — no server, no plugin, fully sandboxed. No server upload.
  • Postgres Playground (PGlite) — A real PostgreSQL server compiled to WebAssembly, running entirely in your browser. Full SQL — JSONB, window functions, CTEs, arrays — with an in-browser schema browser and optional IndexedDB persistence. No server upload, no external database.
  • Multi-Tab Sync Lab — Open in several tabs to see BroadcastChannel presence and chat, live leader election via the Web Locks API, and a hands-on race-condition demo comparing unsafe vs. lock-protected concurrent counter updates. No server upload.

June 2026 (11)

  • YAML / TOML / JSON / XML Converter — Convert between YAML, JSON, TOML, and XML in real time — paste any format, get any other. Perfect for Kubernetes configs, pyproject.toml, pom.xml, and more. No server upload.
  • JavaScript REPL Terminal — Run JavaScript in a sandboxed Web Worker with a full terminal UI. Top-level await, ESM imports from any CDN, console capture, persistent history, and full line-editing. No install, no backend.
  • Network Latency Monitor — Measure real-time round-trip latency to Cloudflare, Google, and jsDelivr CDN endpoints. Charts jitter over time, computes min/avg/max/packet-loss, estimates download speed, and surfaces Network Information API data. No server upload.
  • GPS Route Recorder — Record your GPS route live in the browser using the Geolocation API. View your path on a canvas map with real-time distance, speed, and duration. Import existing GPX files to visualize. Export as GPX or CSV. No server upload.
  • SQLite File Viewer — Open any .sqlite or .db file directly in your browser using SQLite WASM (sql.js). Browse tables, inspect schemas, run SQL queries — no server upload.
  • HAR Waterfall Analyzer — Drop a .har file from Chrome/Firefox/Safari DevTools to get a professional request waterfall, DNS/TCP/TLS/TTFB timing phases per request, resource type breakdown, and performance insights. No server upload.
  • WebRTC P2P File Transfer — Transfer files directly between two browsers — peer-to-peer via WebRTC DataChannels. No server, no upload, no size limit. Exchange a short offer/answer handshake by copy-paste, then files stream browser-to-browser at full speed.
  • MQTT WebSocket Explorer — Connect to any MQTT broker over WebSocket directly from your browser. Subscribe to topics, publish messages, and debug live IoT device streams. Auto-discovers topic trees, pretty-prints JSON payloads, and exports logs. No server upload. Perfect for ESP32, Home Assistant, and IoT dev.
  • Web Bluetooth BLE Explorer — Connect to Bluetooth Low Energy devices wirelessly from your browser. Explore GATT services, read and write characteristics, and stream live sensor data from ESP32, Arduino, health monitors, and custom IoT nodes. No drivers, no app install. Chrome/Edge only.
  • WebSocket Playground — Connect to any WebSocket server, send and receive messages in real time. JSON auto-formatting with syntax highlighting, binary hex mode, message templates, connection timer, and log export. No server upload.
  • EXIF Photo Inspector — Inspect hidden metadata inside photos — GPS location, camera model, timestamps, and more. Strip EXIF data for privacy before sharing. Entirely in your browser, no server upload.

May 2026 (12)

  • Image Steganography — Hide secret text inside PNG images using LSB (Least Significant Bit) steganography — and extract it again. Optional passphrase protection. No server upload.
  • WCAG Color Contrast Checker — Check WCAG 2.1 AA/AAA contrast ratios, get an APCA perceptual contrast score, simulate colour blindness (deuteranopia, protanopia, tritanopia), and find accessible colour pairs. Uses the EyeDropper API to pick colours from anywhere on screen. No server upload.
  • DNS Lookup — Query any DNS record type (A, AAAA, MX, TXT, NS, SOA, CAA) directly from your browser via DNS-over-HTTPS. Auto-detects SPF, DMARC, and DKIM in TXT records. No server upload.
  • Speech Transcription — Transcribe speech to text in real time using your browser's built-in Web Speech API. Timestamped segments, multi-language, export as .txt or .md. No server upload.
  • Screen Recorder — Record your screen, window, or browser tab with optional system audio and microphone — entirely in the browser. No server upload.
  • Cron Expression Parser — Decode any cron expression into plain English, see the next 10 scheduled run times, and understand each field at a glance. No server upload.
  • Text Diff Viewer — Compare two blocks of text line-by-line with highlighted additions and deletions. No server upload.
  • File Hash Calculator — Compute SHA-256, SHA-512, SHA-384, and SHA-1 hashes of any file in your browser. Drag and drop to verify downloads or check integrity. No server upload.
  • JWT Decoder — Decode and inspect JSON Web Tokens. Visualises header, payload, expiry status, and timestamp claims. No server upload.
  • JSON ↔ CSV Converter — Convert between JSON and CSV in your browser. Handles nested objects, quoted fields, and type inference. No server upload.
  • Markdown Preview — Write Markdown and see the rendered HTML live. Supports GFM tables, task lists, and exports to .md or .html.
  • Simple RSS Reader ↗ — Read and browse RSS and Atom feeds directly in your browser

March 2026 (7)

February 2026 (3)

  • M4A to WAV Converter — Convert M4A audio files to WAV (8kHz, mono, mu-law) in your browser using FFmpeg WASM. No server upload.
  • AI Data Studio ↗ — AI-powered data studio for exploring and analyzing datasets
  • WebGPU LLM Chat — Chat with AI models running entirely in your browser using WebGPU. No API keys, no server.

January 2026 (16)