Simon Willison's Weblog: Tools

Slack Emoji Maker

2026-07-31T20:18:05+00:00

SQLite Query Explainer

2026-07-18T17:19:10+00:00

View Mozilla Bugzilla bug reports and run SQL queries against a SQLite database to see exactly how SQLite executes them. The tool annotates every line of `EXPLAIN QUERY PLAN` and low-level `EXPLAIN` bytecode output with plain-English descriptions of what the query planner and virtual machine are doing.

LLM cliché highlighter

2026-07-17T12:11:11+00:00

LLM cliché highlighter

View Mozilla Bugzilla bug reports and analyze text for clichéd phrases commonly found in language model outputs. Paste text into the analyzer or load it from a URL via the Jina Reader proxy to identify matches including "no X, no Y" chains, "sit with that," "you already know," and patterns from Wikipedia's Signs of AI writing guide.

Mermaid to ASCII art (mermaid-ascii)

2026-07-16T14:57:39+00:00

Mermaid to ASCII art (mermaid-ascii)

Convert Mermaid diagram syntax into ASCII and Unicode box-drawing art rendered entirely in your browser using a Go library compiled to WebAssembly. The tool supports flowcharts with labeled edges, subgraphs, and color definitions, as well as sequence diagrams with notes and control flow fragments, while offering customizable padding and output options.

Mermaid to Unicode box art (grok-mermaid)

2026-07-16T00:33:18+00:00

Mermaid to Unicode box art (grok-mermaid)

Convert Mermaid diagram syntax into terminal-style Unicode box-drawing art rendered entirely in your browser using WebAssembly. The tool supports flowcharts, sequence, state, class, and ER diagrams, with other diagram types falling back to a framed source listing. You can adjust the output width, copy the rendered diagram as text, or generate a shareable link to your diagram.

github-code Web Component

2026-07-07T16:18:16+00:00

github-code Web Component

Embed code snippets from GitHub files directly into web pages using the github-code web component. Enter a GitHub URL with a line fragment (e.g., `#L33-L54`) to preview and generate embed code that displays the specified lines without syntax highlighting. Bookmarked URLs are preserved in the page fragment for easy sharing.

HTML table extractor

2026-06-29T23:38:21+00:00

HTML table extractor

Extract tables from pasted content and convert them to multiple formats. Paste HTML, rich text, or plain text containing tables, and the tool automatically detects and displays each table with a preview, then allows you to export it as HTML, Markdown, CSV, TSV, or JSON. You can also import tables directly from Wikipedia by searching for page titles.

OPFS + Pyodide test harness

2026-06-23T18:58:54+00:00

OPFS + Pyodide test harness

Test and manage the Origin Private File System (OPFS) across desktop and mobile browsers with an interactive interface powered by Pyodide. Create, read, and delete files in OPFS, run SQL queries against SQLite databases stored in the file system, and verify persistence across page reloads through a comprehensive activity log and capability detection panel.

— a still that plays

2026-06-17T03:56:10+00:00

— a still that plays

Datasette extras explorer

2026-06-11T15:10:07+00:00

Datasette extras explorer

Query Datasette JSON endpoints and discover available extras by entering a URL and selecting which extras to request. The interface displays the returned JSON response with syntax highlighting and allows you to examine which extras are supported by your Datasette instance, with support for sharing configurations via URL hash parameters.

Pasted File Editor

2026-06-02T04:13:36+00:00

Pasted File Editor

View and manage text drafts with automatic file attachment capabilities. Paste files or text content of 1,000 characters or more to attach them below the editor while keeping your draft text unchanged. Preview attached files in a modal or remove them using drag-and-drop, file selection, or clipboard paste.

markdown-svg-renderer

2026-05-28T19:45:14+00:00

markdown-svg-renderer

View and render markdown content with live preview. Paste markdown directly or load from a raw URL or GitHub Gist, with support for standard formatting, tables, code blocks, and SVG previews with tabbed display for rendered output and source code. Toggle between split editor and full-screen viewer modes.

Mad House — Usborne Creepy Computer Games

2026-05-24T17:14:11+00:00

Mad House — Usborne Creepy Computer Games

Play a retro text-based escape game inspired by 1980s Usborne computer books, where you control doorways in a shifting house to align three exits before footsteps catch you. Use keyboard controls (X/C and N/M) or on-screen buttons to move the near and far doorways left and right, while the center doorway moves unpredictably. The game features authentic CRT phosphor aesthetics with scanlines and a pulsing HUD that tracks your remaining time and door alignment status.

Curly Quote and Em Dash Highlighter

2026-05-21T20:51:47+00:00

Curly Quote and Em Dash Highlighter

Paste text to spot curly quotes, curly apostrophes, em dashes, and non-breaking spaces. The tool highlights each character type with color coding and displays real-time counts, helping identify typographic characters that may have been introduced through word processors or web copy.

QR code generator

2026-05-15T04:00:49+00:00

QR code generator

Generate scannable QR codes from URLs, text, or WiFi network details with customizable styling options. The tool supports multiple encoding modes, including WiFi networks with security settings, and offers various visual styles such as square or liquid designs with adjustable sizes and colors. Generated codes can be downloaded as PNG images or copied directly to the clipboard.