OfflineConvert is a collection of free file converters — images, subtitles, fonts and data — that run entirely in your browser using WebAssembly and native browser APIs. There is no upload step, no queue, no account, and no server that ever sees your files. After a page loads, most tools keep working with your internet connection switched off; that's where the name comes from.
The project exists because the standard online-converter model quietly asks for a lot of trust: your photos, licensed fonts, subtitle scripts or customer spreadsheets get copied to someone else's computer, processed there, and retained under whatever policy applies that week. Modern browsers are powerful enough to make that trade unnecessary — so we skip it entirely, and we show you how to verify that claim yourself with your browser's network tab.
What we publish
The site has three kinds of material. Tools perform a specific conversion and document what changes, what survives and the practical safety limit. Guides cover the work around a conversion: deployment, import validation and troubleshooting. The Lab publishes original measurements with methods, dates, limitations and raw data where available.
How tools and claims are checked
Representative fixtures are converted in a real browser and outputs are inspected for magic bytes, dimensions, transparency, encodings and loadability as appropriate. The automated release gate also watches for outbound requests during conversion. A green test count is evidence for that build, not a promise that every possible file is supported, so each page documents known limits and invites reproducible bug reports.
Facts, corrections, update dates and advertising separation follow the public editorial and testing policy. The project does not invent named experts or hide commercial placement inside recommendations.
How the free site is funded
OfflineConvert has no paid conversion tier, account upsell or sale of uploaded files — there are no uploads to sell. The site may use clearly separated advertising to cover hosting and maintenance. Advertising does not choose tool behavior, test outcomes or editorial conclusions, and ad code is kept away from file controls.
The heavy lifting relies on excellent open-source software — see the versions and licenses on the How it works page. Found a bug, outdated fact or missing tool? Tell us.