Stop downloading files
just to read them.
Filemark renders Markdown, JSON, CSV, and SQL schemas as real interactive views — right in the Chrome tab you're already in. 100% local. Nothing ever uploaded.
docs/launch-plan.md
Launch plan — v0.1
Filemark is live on the Chrome Web Store. Install in one click, or build from source — the renderer is identical either way.
✓ Site live
khanakia.com/apps/filemark · privacy + changelog + demo
import { MDXViewer } from "@filemark/mdx";
The problem
Your browser treats your files wrong.
You open dozens of .md, .json, .csv and .sql files a day. Chrome does one of three unhelpful things with every one of them.
Chrome downloads them
Click a .csv or .tsv link and Chrome dumps a file into Downloads instead of showing it. Now you're hunting for it in Finder.
…or shows raw text
Markdown renders as monospace soup. JSON is an unindented wall. A .sql schema is hundreds of lines you have to read by eye.
So you paste it somewhere
Into an online JSON formatter or markdown previewer — uploading your data to a server you don't control, or opening a whole IDE just to preview one file.
The fix
Same file. Opened the way you meant.
Filemark is a local file viewer for Chrome. It intercepts the files your browser fumbles and renders each one with a real, interactive viewer — instantly, in place, without sending a byte anywhere.
How it works
Installed in a minute. Then invisible.
- 1
Add to Chrome
One click from the Chrome Web Store. No account, no sign-up, nothing to configure.
- 2
Allow file access
Flip “Allow access to file URLs” once on the extension's details page so Filemark can open local files.
- 3
Open any file
Double-click a .md, .json, .csv or .sql file — or paste its path — and it renders in the tab, instantly.
Who it's for
Made for people who live in files.
Developers
Your repo is full of READMEs, configs, fixtures, and schemas. Open any of them, rendered, without leaving the browser or firing up an editor.
AI-assisted coders
Claude Code, Cursor and Codex write Markdown all day. Filemark renders their kanban boards, charts and ER diagrams — and ships a skill so they author them correctly.
Technical writers
Preview docs exactly as they'll publish — GFM, callouts, tabs, math, Mermaid — straight from the file, with live task checkboxes and a table of contents.
File formats
Nine formats, one extension.
- .mdMarkdown
- .mdxMDX
- .jsonJSON
- .jsoncJSONC
- .csvCSV
- .tsvTSV
- .sqlSQL
- .prismaPrisma
- .dbmlDBML
Markdown · MDX
Real markdown.
Not text in a box.
Full GitHub-flavored markdown, KaTeX, Mermaid, syntax highlighting via shiki — plus inline components: callouts, tabs, ADRs, kanban boards, charts, all from plain text.
- Tables that scroll. Code that highlights. Math that renders.
- Drop <Kanban md/>, <Chart src=…/>, <Callout/> right in the prose.
- Lazy-loaded Mermaid and Schema engines — fast on big folders.
guides/getting-started.md
Getting started
Filemark works the moment you point it at a folder. Drag, drop, done.
💡 Pro tip
Press ⌘K to search across every open file.
const ok = true;
| Format | Renderer |
|---|---|
| .md | @filemark/mdx |
| .csv | @filemark/csv |
| .sql | @filemark/schema |
JSON · JSONC
JSON you can
actually read.
Collapsible tree, nine themes, copy-to-clipboard on every node, parse-error pinpoints with line numbers. Better than DevTools, in the file viewer.
- 9 themes including githubDark, nord, monokai, gruvbox.
- Type chips, size hints, collapse-by-depth controls.
- .jsonc supported — comments survive the round trip.
package.json · githubDark
SQL · Prisma · DBML
Your schema,
drawn for you.
Drop a .sql, .prisma or .dbml file in Chrome. Filemark parses it and renders an interactive entity-relationship diagram with foreign keys and column types.
- Three dialects, one diagram. Pan, zoom, click a table.
- Falls back to syntax-highlighted source if the parser stumbles.
- Works offline. No data leaves your browser.
schema.prisma · 3 tables, 2 relations
CSV · TSV
Spreadsheets that
weren't a download.
CSV and TSV files used to trigger a download. In Filemark they open as a real datagrid — sortable, filterable, resizable, with type-aware columns straight from a fence-meta comment.
- Type hints: status badges, tag chips, ratings, currency, dates.
- Multi-sort, column visibility, density toggle, CSV/MD/JSON export.
- Works on local file:// — no server middleware needed.
| # | title | priority | owner | done |
|---|---|---|---|---|
| 1 | Pass platform-design review | P0 | Ada | — |
| 2 | Cut electron-builder release | P1 | Grace | — |
| 3 | Wire Open Folder hotkey | P2 | Linus | ✓ |
| 4 | Ship CWS listing draft | P0 | Aman | — |
| 5 | Promo tile 440×280 | P1 | Aman | ✓ |
Tasks → Kanban
Plain markdown.
Live kanban board.
Author tasks as ordinary bullets with sigils (@owner, !priority, ~due, (project)). Drop one <Kanban md/> tag and the same file renders as a board, grouped however you want.
- - [ ] Ship CWS listing @aman !p0 ~2026-06-15 (launch)
- Group by status, priority, owner, due-bucket — your choice.
- Filterable, recurring, with ADR-style decision logging.
tasks.md · <Kanban md group-by="status"/>
Why not just…
Better than the workarounds.
You already have ways to read these files. Each one costs you privacy, a context switch, or a setup tax.
Why filemark
Built for files you actually
care about reading.
Nine formats, one extension.
One install. Real renderers for everything Chrome can't natively open, with a unified UI across all of them.
100% client-side.
No server, no upload, no analytics, no remote code. Your files are read locally and never leave the browser.
Fast on big folders.
Lazy shiki loading, code-split language grammars, IndexedDB persistence. Open thousands of files without bog.
Let your AI author Filemark docs for you
Drop in the Filemark skill and Claude Code, Cursor, or Codex learns every component, the task DSL, and the gotchas — then writes beautiful kanban boards, charts, and ER diagrams straight into your markdown.
npx skills add thesatellite-ai/filemarkQuestions, answered
- Is Filemark free?
- Yes. Filemark is completely free and open source under the MIT license. There is no paid tier, account, or sign-up.
- Does Filemark upload my files anywhere?
- No. Every renderer runs entirely in your browser. No file contents, search queries, settings, or telemetry are ever sent to any server — you can verify zero outbound requests in Chrome DevTools.
- Which file types does it open?
- Markdown (.md, .mdx), JSON (.json, .jsonc), CSV/TSV (.csv, .tsv), and database schemas (.sql, .prisma, .dbml) — each with a real interactive viewer.
- Can it open local files from my computer?
- Yes. Enable 'Allow access to file URLs' on the extension's details page in chrome://extensions, then double-click any supported file and Chrome opens it rendered. Drag-and-drop and Open Folder also work without that toggle.
- Does it work offline?
- Yes. All rendering libraries are bundled into the extension at build time (Manifest V3, strict CSP, no remote code), so Filemark works with no network connection.
- Can an AI coding agent author Filemark documents?
- Yes. Filemark ships an AI skill that teaches Claude Code, Cursor, or Codex the full component grammar. Install it with: npx skills add thesatellite-ai/filemark.
Install
Add Filemark
to Chrome.
Free, open source, 100% local. One click from the Chrome Web Store — or build from source in 30 seconds.
- 1Clone the repo and run pnpm install && task build.
- 2Open chrome://extensions, toggle Developer mode, click Load unpacked, pick apps/chrome-ext/dist.
- 3On the extension's details page, toggle Allow access to file URLs.