Free File Tools That Run in Your Browser
Most free online converters work by sending your file to someone else's server. For a holiday photo that is fine. For a client's CAD part, a customer dataset or a crash dump off a production machine, it is a disclosure you probably are not allowed to make.
Three of the four below never upload at all — the heavy engines are compiled to WebAssembly and run in the tab, so there is no size cap, no queue and no account. The fourth, DumpReader, does upload, and says so. None of them pay us a referral fee; they are here because they are the tools we reach for.
Where a tool claims to be local, you can check it in under a minute: load the page once, disconnect the network, then convert anyway. A tool that quietly uploads cannot pass that test.
CADverter
Nothing uploadedOpens and converts CAD and 3D files in the browser, running the OpenCASCADE geometry kernel as WebAssembly. 34 formats in, 16 out, 544 conversion pairs.
Pairchute
Nothing uploadedSends a file straight from one browser to another over WebRTC. There is no cloud copy in the middle, so there is no size cap and nothing to expire.
Parquetbay
Nothing uploadedOpens, edits and queries columnar data files in the tab, with DuckDB compiled to WebAssembly for real SQL against a local file.
DumpReader
Uploads, then discardsDecodes a Windows crash dump and names the faulting driver without a WinDbg install or a symbol server round trip. The only one here that uploads: the dump is parsed server-side and the bytes are discarded with the response, which is why it caps at 32 MB.
Each guide covers the limits as well as the workflow — where a browser runs out of memory, what an STL to STEP conversion really returns, why a crash dump can name the wrong driver, and when a plain cloud link is still the better answer.