Peekover
Peekover is a free, open-source browser extension that turns raw markdown files into formatted, readable pages.
It works on markdown files opened from your own disk and on raw files from GitHub, GitLab and Bitbucket.
It asks for no browser permissions and makes no network requests unless you ask it to.
Peekover is in the Chrome Web Store.
The Firefox version is in review at Mozilla and is not listed yet.
To use it in Firefox before then, build it from source (below).
What it does today
- Renders markdown with tables, task lists, strikethrough and bare-URL links.
- Cleans every rendered page with DOMPurify before it is shown.
- Renders markdown files opened from disk (
.md and similar extensions) and raw files on raw.githubusercontent.com, gist.githubusercontent.com, GitLab and Bitbucket.
- Shows a table of contents for documents with two or more headings.
- Lets you sort, filter and copy tables.
- Has light and dark themes and follows your system setting by default.
- Blocks remote images until you choose to load them.
- Has an app page, opened from the toolbar button, where you open a folder and browse its markdown files.
- Can watch a document and update the view when it changes on disk, on the app page and in a tab showing a file opened from disk.
- On the app page, while watching, keeps snapshots of the document on your device, which you can turn off.
- On the app page, compares a document with one of its snapshots or with another file in the folder.
- On the app page, draws Mermaid diagrams, renders math with Temml, and highlights code in JavaScript, TypeScript, TSX, Python, JSON, CSS, HTML, Bash, diff, YAML, Markdown, TOML and SQL.
- On the app page, exports a standalone HTML file, prints to PDF, and copies the document as HTML, plain text or rich text.
- On the app page, has a basic editor with a live preview and a Save button, and asks before discarding unsaved changes.
Limits
- In a tab, snapshots, comparison, diagrams, math, code highlighting, export and editing are not available; open the document on the app page for those.
- Watching does not work for raw files from GitHub, GitLab or Bitbucket.
- In Chromium-based browsers such as Chrome and Edge, files opened from disk need the extension's "Allow access to file URLs" setting turned on.
- Save writes the file back in Chromium-based browsers such as Chrome and Edge; in Firefox it downloads a copy instead.
- In Firefox, watching does not work for a file opened directly from disk.
- In Firefox, on the app page, watching works for a folder dragged in and isn't offered for one chosen with the folder picker.
- In Firefox, files opened from disk need one setting: "Access local files on your computer", under Peekover's Permissions and data in about:addons.
Privacy and permissions
- The extension requests no browser permissions: its manifest says
permissions: [].
- It makes no network requests by default.
- It has no telemetry and no analytics.
- The privacy policy is at https://peekover.dev/privacy/.
- Two builds of the same commit produce identical files; CI checks this on every push to
main and every pull request, and REPRODUCING.md gives the steps to check it yourself.
- Release files carry build attestations:
gh attestation verify confirms a download was built by this repository's release workflow and hasn't changed since.
- Each capability it uses without a permission, such as reading a folder you pick, is listed in PERMISSIONS.md.
- How to report a security problem is in SECURITY.md.
Planned
For the first public release:
- A listing in Firefox Add-ons, in review at Mozilla (Edge Add-ons later).
Later, not yet scheduled:
- DOCX and ZIP export, AI features, and publishing.
Build from source
You need Node 22 (the version in .nvmrc) and pnpm 10.33.0 (the version in package.json's packageManager field; corepack enable provides it).
corepack enable
pnpm install --frozen-lockfile
pnpm build
pnpm exec wxt build -b firefox
pnpm build writes the Chromium build (for Chrome and Edge) to .output/chrome-mv3, and the Firefox command writes .output/firefox-mv3.
To load it in Chrome or Edge, turn on Developer mode on the extensions page and choose "Load unpacked" with .output/chrome-mv3.
To load it in Firefox, open about:debugging, choose "This Firefox", then "Load Temporary Add-on", and pick .output/firefox-mv3/manifest.json.
pnpm test runs the unit tests and pnpm lint runs the linter and the type check.
Licence
Peekover is released under the MIT licence (see LICENSE).
It is free: there is no price, no paid tier and no ads.
The fonts in this repository (Literata, STIX Two Math, Bricolage Grotesque and Sometype Mono) are under the SIL Open Font License 1.1; see NOTICE.
The open-source code Peekover bundles from other projects is listed, each with its licence in full, in THIRD_PARTY_LICENSES.txt, which ships inside the extension.
