About ZasPDF

A suite of 25 PDF tools that run entirely inside your browser.

Why it exists

Nearly every free PDF tool on the internet works the same way: you upload your file to somebody else's server, that server does the work, and it hands the result back. It is a convenient model and, for most documents, a harmless one. It stops being harmless the moment the file is a contract, a medical record, a payroll run, or a client's financial paperwork. At that point you are handing the document to a third party whose retention policy you do not control and who is often in another jurisdiction entirely.

ZasPDF started from a simple observation: modern browsers are already powerful enough to do that work themselves. If the processing happens on your machine, the question "what are they doing with my file?" disappears, because there is nobody on the other end. That is not a promise you have to trust; it is a property of the architecture.

How it is built

The core is an engine written in Go and compiled to WebAssembly, built on the open-source library pdfcpu. That binary downloads once, is cached permanently, and exposes the six structural PDF operations to the browser: merge, split, compress, reorder pages, password-protect and unlock.

The rest of the suite leans on libraries that also run client-side: pdf.js for rendering and text extraction, tesseract.js for OCR, pdf-lib for annotations and signatures, and docx, xlsx, pptxgenjs and mammoth for the Office conversions. None of them needs a server.

The practical consequence is easy to check for yourself: open any tool, disconnect from the network, and watch it keep working. If your file were being uploaded, it could not.

What this costs you, and what it buys you

We would rather be explicit about the model's limits, because they are real. Processing on your machine means your machine sets the ceiling: a PDF of several hundred megabytes can exhaust the memory available to the tab, something a server with 64 GB of RAM would never notice. OCR on a long document takes longer than it would on a server farm. And conversions to Office formats rebuild the content rather than copying it, so heavily designed layouts lose fidelity.

In exchange, your documents never travel, there is no queue, there is no daily file limit, nothing gets watermarked, and everything works without creating an account. For the kind of work we are aiming at, that trade seems worth making — but you should judge it yourself. Each tool page spells out its own specific limitations.

How we are funded

ZasPDF is free and supported by advertising. That is the site's only source of revenue. We think it matters to say so plainly, because it means the website uses cookies and analytics — which can sound contradictory for a product built around privacy. It is not, and the distinction is this: your browsing of the website is measured like on any ad-supported site, while the contents of your files are never collected, because they never reach us. The privacy policy lists every cookie and every provider, one by one.

We do not sell data, we do not charge per tool, and we do not lock features behind a paywall.

Who makes it

ZasPDF is a product of MakawDev, an independent software studio registered and operated out of Puerto Asís, Putumayo, Colombia (the same jurisdiction named in our Terms of Service). It is a small project: there is no support department, emails are answered personally, and the release pace is that of a small team.

The suite currently covers 25 tools, published in English and Spanish on the web (the only two languages with content written and reviewed in-house), with native iOS and Android apps sharing the same engine and offering more interface languages. If something breaks or something is missing, write to us — the contact page reaches the person who builds the product.

Who writes the guides, and how they are checked

The guides are signed "ZasPDF Team" because they are written by the same people who program the tools: a small team at MakawDev with a software-engineering background and years of working with the PDF format at the specification level, not just as users. There are no outside copywriters and no mass-generated content.

Every article follows the same rule: if it states a number (how much a file weighs after compression, how long an OCR pass takes, what remains under a black rectangle), that number was measured with the tools on this site on a file the text describes, so you can repeat the test. When the honest answer is "it depends" or "use something else for this", the guide says so. If you find a mistake, write to us and it gets corrected, with the update date shown on the article.