Sequill: A Free, Private SQLite Editor & Schema Designer That Runs in Your Browser

Why I built it

Every time I needed to look inside a .sqlite or .db file, I had two options: install a desktop app, or upload the file to some random website and hope it wasn't stored somewhere. Neither felt right for a quick look at a database.

So I built Sequill, a SQLite editor and visual schema designer that runs entirely in your browser tab. No server, no upload, no account. It just launched on Product Hunt, and I wanted to share how it works with the dev.to community.

What Sequill is

Sequill is two tools sharing the same set of databases: a SQLite Editor and a Schema Designer. Open a file in one and it shows up in the other instantly.

• Free. No paid tier, no trial, no feature gates.
• Zero bytes uploaded. There is no backend. Your database stays on your device.
• No account. Open the page and start working.
• Offline. After the first visit, the whole app, including the database engine, is cached.
• Installable. It's a PWA, so you can add it to your desktop or phone.
• Real SQLite. It runs the official SQLite 3.54 build compiled to WebAssembly, so files are fully compatible with every other SQLite tool.
• Mobile friendly. The editor has its own phone layout, with tables tucked into a drawer.

What you can do with it

The SQLite Editor

The editor is a fast data grid sitting directly on top of the database. Sorting, filtering and searching all run inside SQLite itself, not in JavaScript, so results are always accurate.

• Browse: virtualised rows for big tables, multi-column sort, search across every column, and filters with 15 conditions combined with AND or OR.
• Explore: pin or hide columns, follow foreign keys to the referenced row, open a row inspector, and preview BLOBs and formatted JSON.
• Edit in place: double-click a cell or just start typing, set NULL in one action, and paste straight from a spreadsheet. Nothing is written until you hit save.
• Write SQL: a console with autocomplete that knows your tables and columns, Ctrl+Enter to run, query plans, saved queries, and timing for every run.
• Import and export: open .sqlite or .db files, import CSV and JSON, export tables or query results as CSV, JSON or SQL, or download a full SQL dump.
• Move to a server DB: generate SQL for PostgreSQL, MySQL and MariaDB, so you can prototype in SQLite and migrate later.

Press Ctrl+K anywhere to jump to any table, view or action. And if you just want to play around, load the built-in Sample Shop database.

The Schema Designer

The designer draws your database as a diagram: every table is a card and every foreign key is a line. You can also change the schema visually.

1. Add a table and name it.
2. Add columns. New ones show in green so you can see what changed.
3. Drag from a column to another table to create a foreign key.
4. Save. Everything is applied in a single transaction.

It also has one-click auto-arrange, focus mode for a single table, colour-coding, and saved drafts per database. SQLite can't alter every part of a table in place, so when a change needs it, Sequill safely rebuilds the table for you.

How it works under the hood

Sequill has no backend at all. It's a set of static files, and everything happens in the browser.

1. SQLite compiled to WebAssembly. The core is the official SQLite WASM build. Since it's the real engine and not a reimplementation, every query and schema change behaves exactly like native SQLite.
2. A Web Worker. SQLite runs off the main thread, so scrolling the grid, typing in the console or dragging tables never freezes, even during a heavy query.
3. OPFS for storage. Databases are stored in the Origin Private File System. It gives the worker fast, file-like access, so SQLite reads and writes real files instead of holding everything in memory.
4. Header parsing without the engine. The landing page's "Try your own file" reads a database's header and first page directly, showing page size, encoding, journal mode, SQLite version and tables instantly.
5. Offline-first PWA. Every asset, including the WASM engine, is cached after the first visit.
6. Next.js, exported as static files for the UI.

The design principles were simple: privacy by architecture rather than by promise, let SQLite do the work instead of re-implementing it in JS, and stage every change until you save.

A few honest trade-offs

• When you open a file, Sequill copies it into OPFS. Your original file is never modified.
• If you clear the site's data, your databases go with it. Sequill requests persistent storage, but always download a copy of anything important.
• Only one tab can use the database at a time, because the OPFS storage handle is exclusive.
• The size limit is your browser's storage quota for the site, and very large exports are limited by memory.

Who it's for

• Developers who need to quickly inspect or fix a .db file from an app, test or mobile build.
• Anyone prototyping a schema in SQLite before moving it to Postgres or MySQL.
• People working with sensitive data who can't upload files to an online tool.
• Students learning SQL who want a playground without installing anything.

What's next

I'm adding MCP (Model Context Protocol) support so AI assistants can read your schema, run queries and help explore your data, with you in control of access. I also plan to support local AI agents, so you can generate queries or get schema help without sending your database to the cloud. If you have ideas for what an AI agent should do with your databases, I'd love to hear them.

Try it

Sequill is live and free at sequill.adibitz.com. Pick a file, start an empty database, or load the sample shop. Nothing to install, no account to create.

• Open the editor
• Open the schema designer
• Sequill on Product Hunt

It launched on Product Hunt today, so an upvote would mean a lot. More than that, I'd really like your feedback: what's missing, what's broken, and what would make you use it every day. Drop it in the comments below.

Originally published on adibitz.com.