About ConvertKit
ConvertKit is a free suite of image, PDF, and document tools that runs entirely in your browser. Pick a file on your computer, and it is read, transformed, and written back on your own machine — it is never uploaded to a server. There is no account to create, no watermarks on the output, and no daily quota hiding behind a paywall. This page explains who runs the site, how the tools work, what we do and do not collect, and how a service with no price tag actually pays for itself.
Who we are
ConvertKit is built and maintained by a small, independent startup based in Pakistan. We are a compact team of developers — no sales team, no support call center, no account managers. The people who write the code are the same people who read the messages that come through the contact form, and the same people who fix what those messages report. That is the whole company, and we think it shows in the product: the tools do one job carefully instead of ten jobs badly, and every limitation is published rather than buried.
We work in public the only way a small team can — by shipping. The site has a public guides library where we document the practical knowledge behind the tools, an accessibility statement with the work still outstanding, and legal pages (privacy, cookies, terms) written to be read rather than to be survived.
Why we built it
Most online converters work the same way: you choose a file, it uploads to someone else’s server, a queue processes it, and you download the result. For a holiday photo that is harmless. For a signed contract, a medical record, a client’s unreleased design, or a company’s internal spreadsheet, it means handing a copy of the document to a third party you have never met, storing it on hardware you cannot see, under a privacy policy you probably did not read.
We did not accept that trade-off as inevitable, and it turns out the trade-off is unnecessary: modern browsers are powerful enough to do the work locally. A JavaScript engine, the Canvas API, and a set of open-source parsing libraries can resize an image, rebuild a PDF, or re-render a Word document without a single byte crossing the network. So that is what we built — the converter without the upload. The file stays on your machine, and the only thing the server ever sends you is the web page itself.
How the tools work
When you drop a file into one of the workspaces, the browser reads it from your disk with the standard file API into memory. Images are decoded into a bitmap and drawn onto an HTML canvas, where every operation — resize, crop, rotate, compress, format change — is a drawing step; the finished canvas is then encoded as the format you chose (PNG, JPEG, WEBP, AVIF, BMP, GIF, TIFF, or ICO) and handed back to you as a download. PDFs and documents follow the same principle: pages and text are parsed with client-side libraries, restructured in the tab, and written out as a new file.
Because processing is local, three things follow directly. Privacy: no copy of the file exists anywhere but your device, and closing the tab discards the working data. Speed: there is no upload, no server queue, and no time-of-day congestion — a batch takes as long as your hardware takes, not as long as someone else’s. Availability: the tool works the same on the thousandth use as on the first, because there is no per-request infrastructure cost to ration.
What you can do here
The suite covers the conversions people actually need, in every direction that matters:
- Image conversion between PNG, JPEG, WEBP, HEIC, AVIF, BMP, GIF, TIFF, and ICO — with a quality slider, resize by pixels or target file size, and batch queues.
- Image editing in the workshop: resize, crop, rotate, grayscale, watermark, and social media presets, previewed before you download.
- Document conversion across PDF, DOCX, HTML, Markdown, TXT, CSV, JSON, and Excel — including DOCX rendering that preserves fonts, tables, and page layout rather than approximating them.
- PDF utilities: merge, split, rotate, and PDF-to-image, all preserving the original page objects rather than re-rendering them.
Batches run up to 20 files at a time; individual files up to 25 MB (100 MB for PDFs); results download individually or as a single ZIP. If you want the reasoning behind the formats rather than the tool, the guides cover topics like choosing between image formats, compressing images for the web, and splitting PDFs correctly — the same advice we give ourselves when building the tools.
What we collect — and what we never see
Your files never reach us, so there is nothing for us to store, leak, or train on: the tools do not use AI to read, analyze, or learn from your documents. What we do process is limited to what a website inevitably touches. The contact form collects your name, email, and message so we can reply — protected by Cloudflare Turnstile and rate limiting. If you consent to cookies, Google Analytics measures traffic and Google AdSense selects and measures ads; without consent, those stay off. The full breakdown lives in the privacy policy and the cookie policy, and we do not sell, rent, or trade personal data.
How a free site pays for itself
Straightforwardly: advertisements. ConvertKit shows ads (via Google AdSense) and otherwise costs nothing — no premium tier, no usage-based billing, no upsell screen between you and your file. Ads fund the development, the hosting, and the bandwidth that the site does use, which is almost entirely the delivery of the web pages themselves. If you would rather not see them, the cookie policy explains the consent controls, and browser ad blockers work like they do anywhere else. We think this is the most honest arrangement available: a free tool, paid for by advertising, with a privacy policy that says so in plain words.
Limits we do not hide
Local processing means the practical limits are your device’s memory and browser, not ours — which is why the tools publish theirs plainly: 20 files per batch, 25 MB per image or document, 100 MB per PDF. Unusually large or unusual files can occasionally defeat a browser parser; when that happens the error is shown honestly, and splitting or re-exporting the source usually clears it. We would rather state a real limit than advertise an unlimited service that silently fails at the edges.
Getting in touch
Bug, format request, accessibility barrier, or something the tools do not handle yet? Use the contact form — a person on the team reads every message and replies, usually within a couple of working days. Accessibility issues are tracked against our accessibility statement; privacy questions are answered in the privacy policy or by asking directly. We are a small team, and that is exactly why the distance between reporting a problem and the person who can fix it is one email.