Chrome extension · v1.0.0
Markdown and JSON, in the tab you already opened — same URL, so bookmarks, history and reload keep working.
# Payments service The service that moves money. **Read this before touching it.** | Endpoint | Method | Idempotent | |---|---|---| | /charges | POST | yes, via key | | /refunds | POST | yes, via key | ```bash pnpm run dev --filter payments ``` - [ ] Rotate the sandbox key - [ ] Backfill `charge.created_at`
The service that moves money. Read this before touching it.
| Endpoint | Method | Idempotent |
|---|---|---|
| /charges | POST | yes, via key |
| /refunds | POST | yes, via key |
pnpm run dev --filter payments
Why another one
The incumbent has 100,000+ users and 4.7 stars, and it earned them: it solved rendering and stopped there. It also ships 11.58 MB to display a README, and it speaks exactly one file format. FileLens speaks two, in 117 KB — roughly a hundredth of the weight.
The bars are to scale — FileLens's is 1% of the other, which is the honest picture and looks like an error. Only 19 KB of that runs before FileLens has decided the page is even its business, and each format's renderer loads only when you open that kind of file, so reading a README never costs you the JSON code.
The wedge is not a longer format list. It is the two formats a browser actually renders, done properly, small, and private. Everything below follows from that sentence — including the features that are deliberately missing.
Two formats
#installation in the address bar jumps
where you expect
What comes with it
Nothing here is behind a paywall, because there is no paywall. FileLens is free on the Chrome Web Store, and it has no paid tier planned.
A heading tree with a filter box, tracking your scroll position as you read. Collapse the sidebar with s; it remembers which panel you left open.
The Style panel is a visual editor for 40 design tokens — fonts, sizes, spacing, colours, code blocks, rules — with live preview. Your changes persist and follow your Chrome profile.
Save the file in your editor and the page re-renders where you were. It works by the page asking the extension to re-read the one document that asked — and it is one switch away from off.
Light and dark, each drawn deliberately rather than colour-inverted, plus a System setting that follows your OS.
s sidebar · r raw source · f fullscreen · Esc leaves it. Keys are ignored while you are typing in a field.
Per-file scroll memory, capped at the 200 most recent files and kept on this device only — those keys are paths on one machine's disk, and syncing them would broadcast what you read.
One setup step
Chrome blocks every extension from file:// pages until you allow
it by hand. It is not a permission an extension can request, prompt for, or grant in
code — which is why so many viewers in this category simply ask for access to every
website instead.
FileLens opens a setup page on install that shows you whether the switch is on, with the address ready to copy. That page re-checks every time you come back to the tab, because Chrome fires no event when the switch changes. You can reopen it any time from Details → Extension options. If FileLens seems to be doing nothing at all, this is almost certainly why.
chrome://extensionsChrome will not let a link take you there, so paste it into the address bar.
The card carries the extension's own permission list, in Chrome's words.
That is the whole setup. Open any .md or .json file.
Private by construction
Most extensions in this category ask to read and change your data on all websites before you have used them once. FileLens asks for no website at all, and it makes no network requests — not to us, not to anyone. There is no server to send anything to.
| At install | Answer |
|---|---|
| Host permissions | None |
| Permissions showing a warning prompt | None |
| Permissions requested |
storage, scripting, activeTab — none of
which grants access to any site
|
| Pages it runs on | file:///* only, until you enable a specific site yourself |
| Optional host permissions | Declared, granted one origin at a time, at your request, each with Chrome's own confirmation |
| Analytics, telemetry, crash reporting | None of it exists |
An end-to-end test renders the whole fixture corpus in a real browser, records
every network request the browser attempts — including from the background
worker — and fails if any of them is not a local file or one of FileLens's own
packaged files. A source grep only proves nobody wrote a fetch; this
catches a dependency, a stylesheet or a font doing it.
An image loaded from the internet by a document you were emailed is a read receipt: it tells that server you opened the file, when, and from where. FileLens leaves a marker where the image would be, so you can see it made a decision rather than wonder why something is broken. Links are unaffected — clicking one is you choosing to.
With live reload on, FileLens re-reads the file you are looking at about once a second so it can re-render when you save. That is a local read of a document you already opened, restricted to that exact address by the browser's own record of which document asked, and nothing is transmitted. One switch turns it off.
Every number on this page came from an instrument rather than an estimate — the size from the build gate, the network claim from a real browser, the dropped formats from measuring what Chrome actually does with them. Where measuring contradicted the plan, the plan changed and this page says so.
What it does not do
An earlier plan promised CSV, YAML, TOML, XML, diff and log as well. Measuring Chrome's actual behaviour killed that, and the promise went with it rather than shipping caveats. Being clear about this is more useful than a longer feature list.
.csv and .yaml cannot work at all
Chrome downloads them instead of showing a page, so no extension ever gets a
document to render. The header rewrite that rescues served files has nothing to act
on for file:// — there is no response to modify. Measured, not assumed.
.toml, .diff, .log, .xml are left alone
Deliberately. They stay listed in the source as recognised and deliberately
unhandled, which stops content sniffing from claiming a .log whose
first line happens to be a JSON record. .xml is not even plain text —
Chrome opens its own tree viewer, a different DOM entirely.
.jsonc and .json5 are not handledA strict parser rejects them, and telling you a valid file is broken is worse than not opening it.
- [ ] thing shows the brackets literally. Common in READMEs, and it
needs a parser plugin that is not in yet.
Fenced blocks render as monospace with their own background and border, but the code inside is not coloured by language.
FileLens is a reader. There is no editing, no saving, and no writing to any file you open.
Questions
Yes — completely. Free on the Chrome Web Store, with no paid tier, no trial, no account and no ads. Every feature on this page is in the build you install, because there is no other build.
Turn on Allow access to file URLs on the FileLens card at
chrome://extensions. Chrome blocks every extension from
file:// pages until you do, and it will not let an extension request
that for you. FileLens's setup page shows you the current state and re-checks each
time you return to the tab.
Yes, on sites you enable one at a time. FileLens holds no host permissions at
install; you enable an origin from the toolbar popup, Chrome asks you to confirm,
and only that origin is granted. You can see the list in settings, remove any of
them there, or withdraw them from chrome://extensions. Removing a
site hands the permission back to Chrome rather than keeping it.
No — and that was a deliberate architectural decision, not a side effect. FileLens rewrites the page you are on instead of redirecting you to a viewer page, so bookmarks, history, reload, anchors and sharing a path with a colleague all keep working.
No. FileLens makes no network requests. File contents are never stored or transmitted, no file names or paths are recorded, and there is no install ID, device ID or user ID — nothing distinguishes one installation from another.
Open DevTools and watch the Network panel stay empty. See the privacy policy for the complete account, including the live-reload caveat.
Because it is hosted on a remote server, and loading it would tell that server you opened the file. FileLens blocks remote images in local documents by default and leaves a visible marker, so you can tell a decision was made rather than assume something is broken. There is a one-click opt-in when you do want them.
It is not on every page. The only static content script in the manifest matches
file:///*, and there is a standing rule in the source against
widening it. Where it does run, 19 KB loads before FileLens has decided the page
is even its business; the format's renderer loads only after that.
Theme, style overrides, sidebar state, preferences and your enabled-site list use
chrome.storage.sync, so they roam with your own Chrome profile —
Chrome's mechanism, between your own devices, never through us. Your per-file
scroll positions deliberately do not sync.
Install
FileLens is free — no account, no trial, no paid tier, and nothing to upgrade to. Chrome installs it in one click and keeps it updated from then on.
Install Extension — FreeOne step after installing: turn on Allow access to file URLs, as described above. Chrome will not let any extension do that for you, and local files stay untouched until you do.
A document that came out mangled, a JSON file that would not open, a format worth reconsidering. There is no in-app reporting — that would need a network request — so email and GitHub issues are the whole support channel, and both are read.