Compare PDF Documents

PDF Comparison Tool is a PDF tool that runs in your browser. Visually compare two PDF files. Each page is rendered and diffed pixel-by-pixel, highlighting all changes in red. The page you are reading is the same workspace you will use to do the work: pick a file or paste your input, choose the options that matter to you, and the tool produces the result on your device.

PDF Comparison Tool is shaped around the recurring needs of two audiences: freelancers sharing scanned receipts, who use it as a quick utility between bigger tools, and small-business owners sending invoices, who use it as their primary way of getting the job done. Both groups get the same defaults and the same speed.

Reach for PDF Comparison Tool when you need a predictable result on a single file. The page works on the first visit, the controls are visible without a menu, and the output is delivered the moment the engine finishes.

PDF Comparison Tool runs on Mozilla's PDF.js renderer — an open-source, well-audited engine that performs the PDF document workflow natively in the browser. It accepts PDF and produces output that opens in any standard PDF viewer. Per-run input is capped at 200 MB.

The execution model is straightforward: your file is bytes in the tab's memory, the engine reads those bytes, computes the result, and hands the result back to the browser. The transformation happens locally, which is why the tool keeps working when your network connection drops mid-job and why it produces the same result every run for the same input.

PDF Comparison Tool sits in a small group of related tools. Useful neighbours include PDF to Text Extractor, PDF to Black & White, Interleave PDF Pages, and Extract Single PDF Page. They are designed to compose: the output of one is a sensible input to the next, so a multi-step task is usually a sequence of single-click operations.

Constraints worth knowing about: inputs are capped at 200 MB to keep memory usage in a sensible range, multiple files can be processed in a single run, and the tool must be loaded over HTTPS for the in-browser engine to work. These are properties of the architecture.

Some notes on the design of PDF Comparison Tool. The page is intentionally narrow: one input, the controls relevant to the task, and one output. Adding unrelated features would make the common case slower for the majority of users, so the surface is held to what people actually use.

Output handling is intentionally boring: PDF Comparison Tool produces `pdf-comparison.pdf` and triggers your browser's standard "save" behaviour. If you have a default download folder configured, that is where it will land. There is no Favtoo-side history of jobs you have run.

PDF Comparison Tool is structured around the idea that a useful tool should be its own page. Open the page, do the work, close the tab — the page is the entire product. There is no onboarding flow because there is nothing to onboard into.

PDF Comparison Tool fits the gap where opening a desktop app feels heavy and writing a script feels overkill. The page handles the common PDF document workflow task with sensible defaults so a single visit usually completes the job; for highly specialised work, a dedicated desktop application can offer more knobs to turn.

If you want to get the most out of PDF Comparison Tool, three small habits help. Drag-and-drop is faster than the file picker once you get used to it. The keyboard shortcut for downloading the result is whatever your browser uses for "save link as," because the result is a normal download. And if you are working on a sensitive file, processing in an Incognito or Private window is a good extra layer — it leaves no trace in browser history when the tab closes.

For most failure modes, refreshing the page and re-running the job is enough — the engine has no persistent state to corrupt. If the same input fails twice in a row, the input itself is most likely the problem (a truncated file, an unexpected variant of the format, or a stream the engine does not recognise).

If PDF Comparison Tool solved your problem, sharing the page link with someone who has the same problem is the most useful thing you can do. The catalog grows mostly through word of mouth; visitors arriving through a recommendation tend to be the ones the tool serves best.