An open source screenshot extension for Chrome, Edge and Firefox

The core extension is licensed AGPL-3.0-or-later. The repository is public, you can build it yourself, and the privacy claims on this site are things you can confirm by reading the code rather than trusting a policy page.

What's open, and what isn't

Being precise about this matters more than claiming everything is open:

• Open (AGPL-3.0-or-later): the whole capture pipeline — full-page stitching, visible-area and selected-area capture, cropping, annotation, blur, undo, and PNG and PDF export.
• Proprietary: the watermark module, which is the single paid feature. It is a separate component, not part of the AGPL core.

So every feature you can use without paying is a feature you can read the source of.

Why one feature is paid, and why that one

A free extension gets paid for somehow. The usual answers are ads, telemetry sold on, a subscription, or an upload step that turns your captures into someone else’s storage business. None of those are here: no ads and no ad-tracking code, no analytics or telemetry in the extension at all, and nothing you capture is uploaded. What funds it instead is one feature — tiling a logo or text watermark across an export — at $5 for 1,000 credits, paid once, with no subscription and no renewal.

Shipping that as a separate proprietary module, rather than as an AGPL feature sitting behind a licence check, keeps the boundary in one place you can see: the watermark module is the closed part, and capture, the editor, blur, and PNG and PDF export are in the AGPL repository.

Why AGPL

AGPL keeps derivatives open. If someone ships a modified OpenCapture as a hosted service, they have to publish their changes too. For a tool whose whole point is that you can audit it, a weaker licence would undercut the guarantee.

What the licence asks of you is nothing at all if you are only using the extension. Reading the code, running it, and building your own copy are unconditional. The obligations begin when you distribute a modified build or run one as a service for other people — then your changes have to be published under the same terms. The full text is on gnu.org; the summary is here, the binding version is there.

What reading the source settles

Every privacy claim on this site is a statement about what the extension does while it runs, and each one has a place in the code that corresponds to it: which network requests exist, what gets written to extension storage, what the capture pipeline touches. A closed extension can only be audited from the outside — watch its traffic, infer the rest. With the source you can work in the other direction: read what it is built to do, then watch it do that.

The runtime side of it has its own page. The four permissions, what each one grants, and how to confirm in DevTools that a capture makes no requests are set out in why nothing gets uploaded. What this page adds is narrower, and in the end it is the more useful half: those claims are falsifiable. If the code did something other than what the privacy policy describes, anyone could open the repository and say so in public, with a line number.

What open source does not settle

Three limits worth stating plainly, because “open source” often gets used as a synonym for “private” and it is not one:

• A licence is not a privacy guarantee. An extension can be MIT-licensed and still upload every capture to a server. The two questions are independent, which is why this site does not stop at the licence: the permissions are listed, and you can watch the network panel while a capture runs and see that nothing is requested.
• A public repository is not proof of what the store shipped. Reading the source tells you about the source. Building it yourself means you are not relying on the store's bundle at all.
• Auditable is not audited. A published repository is an open invitation, not a review that has already happened. What the licence buys is that someone can read it — a security reviewer, an IT department deciding whether to allow the extension, or the one person on a team who reads manifests for fun.

Build it yourself

Reading the source is one thing; building it is stronger. If you build the bundle, nobody swapped it between the repository and the store listing. The Build from source section of the README covers it: Rust with the wasm32 target and Node 22, then npm run build for Chrome or npm run build:firefox for Firefox, and load the result as an unpacked extension.

Two things are worth knowing if you do. What changed between builds is on the releases page, which is where version numbers live rather than on this site, so nothing here can go stale against the store listings. And if a build you made behaves differently from the one a store handed you, that is worth an issue rather than a shrug — it is the exact discrepancy this whole arrangement exists to surface.

Contributing and reporting problems

Bugs and feature requests go to Issues; open-ended questions to Discussions. Security reports should go through a private channel rather than a public issue.

Which of the other extensions are open source

It is a shorter list than the search results suggest. Checked against each product’s own site, store listing or repository, last reviewed September 2026:

• GoFullPage has a public repository under MIT, but it has had only minor commits since 2018 and the version shipping today is built from a private branch, so the code running in your browser is not published. OpenCapture vs GoFullPage.
• FireShot is closed source. It also has the widest feature set of the three, which is the trade worth being honest about. OpenCapture vs FireShot.
• Awesome Screenshot has no public repository, though its Firefox build is listed as MPL-2.0. OpenCapture vs Awesome Screenshot.

None of that makes them unsafe, and nothing here is evidence that any of them mishandles the pages you capture. It means that with those three the privacy claim is something you accept from the vendor, and here it is something you can check yourself. If that distinction does not matter for the pages you point a screenshot tool at, it is a fair reason to stay where you are — and the side-by-side comparison covers everything else: price, where each free tier stops, and what each one does better.