Tools
Filters: Sorted by date
Tool
Contact form
— Submit contact information through this form that demonstrates client-side validation using only HTML5 and CSS. The form validates required fields, email addresses, phone numbers, and message length in real-time as users interact with inputs, displaying visual feedback with checkmarks for valid entries and error indicators for invalid ones. No JavaScript processing occurs—this is a demonstration of modern web standards for form validation without backend submission.
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Gemini Prompt
— Generate responses from Google's Gemini API with support for system prompts, model selection, and streaming output. The interface stores your API key securely in local storage and maintains a history of system prompts for quick reuse. Markdown formatting is automatically rendered in the output area, and you can copy responses to your clipboard with a single click.
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Gradient image generator
— Generate customizable gradient images with multiple pattern overlays and effects. This tool provides controls for linear, radial, and conic gradients with adjustable colors, along with options for layering various patterns including noise, geometric shapes, and textures. Additional features include film grain, vignetting, and blend mode controls to fine-tune the visual appearance, with the ability to export the final result as a PNG image or save and restore settings as JSON.
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Python Comment Stripper
— Remove all comments from Python source code while preserving strings, docstrings, and code structure using the `tokenize` module running on Pyodide. Paste your Python code into the input panel, and the tool automatically strips comments in real-time, with the ability to copy the cleaned output to your clipboard. The application runs entirely in the browser without requiring a local Python installation.
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Pyodide REPL
— Execute Python code directly in your web browser using Pyodide, a port of CPython to WebAssembly. This REPL provides an interactive Python environment with support for multiple Pyodide versions, single-line and multi-line input modes, and command history navigation. The interface is optimized for both desktop and mobile devices, with a dark theme and responsive layout that prevents content from being hidden behind on-screen keyboards.
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GIF Dissector
— Parse and visualize animated GIF files by extracting individual frames, timing data, color palettes, and detailed metadata. Upload a GIF file to instantly decompose it into its constituent frames with precise delay measurements, disposal methods, transparency information, and global color table analysis. The tool renders composited frames to show exactly how the animation appears, while providing comprehensive technical details about the image structure and properties.
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SQLite AST
— Parse SQLite SELECT queries into abstract syntax trees and view the results in JSON and Python representations. This tool uses the sqlite-ast library running in your browser via Pyodide to analyze SQL syntax and display both the dictionary-based parse tree and a rich pretty-printed representation. It supports complex queries including compound selects, common table expressions, and window functions, and can display partial parse results when encountering syntax errors.
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Minesweeper
— Play a classic Minesweeper game directly in your browser with support for three difficulty levels: Easy, Medium, and Hard. Use left-click to reveal cells and right-click to place flags, or toggle between reveal and flag modes on mobile with long-press support. The game features a timer to track your speed, mine counter to monitor remaining flags, and immediate visual feedback when you win or hit a mine.
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Directory Explorer Demo
— Explore the contents of a local directory in your browser with an interactive file tree viewer and search functionality. This tool demonstrates the capabilities of the `webkitdirectory` input attribute to access folder structures and analyze file distribution. Once a directory is selected, view detailed statistics about file counts, total size, and file type breakdown, with options to filter by name and file extension.
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Bookmarklets Collection
— Access a collection of practical bookmarklets for web development and general browsing tasks. Each bookmarklet can be installed by dragging it to your bookmarks bar on desktop browsers or by copying the code for mobile Safari. The collection includes tools for revealing page anchor points and viewing page source code with formatting options, all presented with detailed documentation and source code inspection capabilities.
Tool
Seamless Sandboxed Iframe Prototype
— Embed untrusted content safely within a webpage using a sandboxed iframe that automatically adjusts its height without allowing cross-origin access. The prototype uses `postMessage` to communicate height changes between the sandboxed iframe and parent page, enabling seamless content display while maintaining security restrictions. Various content examples demonstrate how the sandbox handles dynamic content, images, and attempts at malicious behavior.
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Lobsters Latest Comments Bookmarklet
— View Lobste.rs comment threads with a chronological "Latest" tab that displays all comments in a flat, newest-first layout alongside the original nested view. The bookmarklet adds reply-to links showing which comment each reply targets, and clicking timestamps in the Latest view smoothly navigates back to the threaded view with the selected comment highlighted for easy reference.
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v86 Linux Emulator
— Run Linux commands directly in your browser using x86 emulation powered by v86. The emulator boots a minimal Linux distribution and provides a terminal interface where you can execute shell commands and view their output in real-time. Boot times typically range from 10-30 seconds depending on your device and connection speed.
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Hyperviz
— Create real-time audio-reactive visualizations with eight distinct modes including plasma, particles, tunnel effects, kaleidoscope patterns, Matrix rain, terrain, fire, and starfield animations. The visualizer captures frequency data from your microphone and responds dynamically to bass, mid, and high frequencies, with beat detection triggering visual flashes and intensity changes.
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Software Heritage Repository Retriever
— Download archived Git repositories from Software Heritage, the universal archive of software source code. This tool queries the Software Heritage GraphQL API to locate repositories and creates downloadable bare Git archives through the vault service. Enter a repository URL to retrieve the latest snapshot and access detailed archive information including the Software Heritage identifier (SWHID) for future reference.
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PG&E Outage Map - Half Moon Bay Area
— Track power outages affecting the Half Moon Bay area with this interactive map displaying real-time PG&E outage data within a 15-mile radius. The application visualizes outage locations as point markers and affected areas as polygons, while displaying key statistics including the number of outages, impacted customers, and affected regions. Custom markers can be added by providing a URL parameter, and the map automatically refreshes every five minutes to ensure current outage information.
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MicroQuickJS Code Executor
— Execute JavaScript code in a lightweight MicroQuickJS sandbox environment running via WebAssembly, with results displayed directly on the page. The sandbox supports ES5-like JavaScript features and automatically saves your code in the URL for easy sharing and recovery. Choose between optimized and original WebAssembly versions, try built-in examples, and use Ctrl+Enter to quickly run your code.
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Photo print layout
— Create custom photo print layouts for A4 pages with adjustable grid configurations, image fitting options, and portrait or landscape orientations. Users can add photos by uploading files or dragging and dropping them directly onto the page, then remove individual photos or clear the entire layout before printing. The preview displays actual print dimensions, allowing precise control over how photos will appear on the final printed output.
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JSON Diff Tool
— Compare JSON documents side-by-side to identify additions, removals, and modifications between two versions. The tool displays differences with color-coded highlighting and provides character-level detail for string changes, making it easy to spot exactly what has changed. Preloaded examples are available to explore common use cases like configuration updates, user profile changes, and API response comparisons.
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Claude Code Timeline Viewer
— View Claude Code session `.jsonl` files as an interactive timeline with customizable filtering and search capabilities. This tool displays events chronologically, extracting conversation messages, tool calls, and file snapshots with formatted previews of text content, code blocks, and embedded images. Use the file picker, drag-and-drop, paste input, or URL fetch to load your session data and explore it with timezone switching, content-type filters, and easy JSON export.
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Codex Timeline Viewer
— View Mozilla Codex rollout timeline events by uploading or pasting a JSONL file to explore the sequence of messages, function calls, and system events with interactive filtering and search capabilities. Each event displays its timestamp in your local timezone or UTC, with detailed views showing formatted content, tool parameters, and reasoning blocks for supported event types.
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QuickJS Code Executor
— Execute JavaScript code in a sandboxed QuickJS WebAssembly environment with a built-in synchronous `fetch()` function for retrieving remote content. Code is automatically encoded in the URL hash, allowing you to easily share executable snippets with others. The interface provides a collection of ready-to-run examples covering common programming tasks and JavaScript features, making it useful for learning, testing, and demonstrating code behavior.
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Is it a bird?
— Determine whether images contain birds using OpenAI's CLIP model running directly in your browser through Transformers.js. Upload images by dragging and dropping, pasting from your clipboard, or selecting files, or use your device's camera for real-time analysis. The tool processes all images locally with no data sent to external servers, and includes a webcam mode with pinch-to-zoom functionality for mobile devices.
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Blog to Newsletter
— Convert blog posts and other content from Simon Willison's website into a formatted HTML newsletter ready for Substack distribution. The tool fetches recent entries, blogmarks, quotations, and TILs from a Datasette backup, allows customization of the time period and content filtering, and provides drag-and-drop reordering of stories.
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Clipboard Backup
— Save and manage clipboard content across multiple formats including text, HTML, RTF, and images with this clipboard backup tool. Paste any content from your clipboard to automatically create a backup that can be restored later or downloaded in its original format. All backups are stored locally in your browser using IndexedDB, giving you persistent access to your clipboard history without any external uploads or server storage.