Drop a DOCX, spreadsheet, CSV, Jupyter notebook, PDF, or paste a URL — and get clean, portable Markdown in an instant. Every conversion runs 100% in your browser, with zero uploads.
Processing happens 100% in your browser — nothing is uploaded.
100% Local Processing — Your files never leave your device
Every conversion runs in your browser using WebAssembly and Web Workers. Your files are never uploaded to any server.
Blazing Fast (INP-Optimized)
Heavy parsing is offloaded to Web Workers so the interface never freezes — even on large spreadsheets or PDFs.
Pristine Markdown Output
Battle-tested libraries like Turndown, Mammoth and SheetJS produce clean, portable Markdown you can trust.
Free & Open
No accounts, no paywalls, no tracking of your documents. Also available as an NPM SDK and an embeddable widget.
Privacy-First Processing
MarkdownForge is built on a single, non-negotiable principle: your documents never leave your device. Unlike typical online converters that upload your file to a remote server, process it there, and send the result back, MarkdownForge does all of its work inside your own browser tab.
When you drop a file, it is read locally with the browser’s FileReader API and handed to a dedicated Web Worker — a background thread that runs the parsing libraries (Turndown, Mammoth, SheetJS, pdf.js and others) entirely on your CPU. The generated Markdown is rendered back to the page without a single byte of your content touching the network. There is no upload step, no temporary server-side copy, and nothing to delete afterwards, because nothing was ever transmitted.
This architecture has three concrete benefits:
Confidentiality by design. Sensitive contracts, financial spreadsheets, and unpublished research stay on your machine — ideal for regulated environments where uploading data to a third party is prohibited.
Speed. Removing the upload/queue/download round-trip means most conversions complete in milliseconds, even offline once the page has loaded.
Transparency. The only optional network request is the URL-to-Markdown feature, which fetches a public web page through a stateless CORS proxy that stores nothing. Every other converter is provably offline.
The same engine is open for inspection and available as an NPM SDK, so you can verify the privacy claims yourself or run the conversions inside your own application.
Frequently Asked Questions
How much faster is client-side conversion than server-based tools?
Client-side conversion removes the two slowest parts of a traditional online converter: uploading your file to a remote server and waiting in that server's processing queue. MarkdownForge parses the file directly in your browser, so a typical DOCX or CSV converts in tens of milliseconds — usually before a comparable upload would even finish. There is no network round-trip, no cold-start latency, and no rate limiting, because your own CPU does the work.
How does MarkdownForge handle a massive 50MB PDF without crashing the browser?
It uses sequential page-by-page streaming. Instead of loading the whole document into memory at once (or extracting every page in parallel with Promise.all, which would keep all pages resident and trigger Out-Of-Memory crashes), the PDF engine processes exactly one page at a time inside a Web Worker. After each page's text is extracted it calls the page's cleanup routine and drops the reference, so the browser's garbage collector reclaims that memory before the next page loads. Peak memory therefore stays roughly constant — about one page's worth — no matter whether the PDF is 5 pages or 500. You see live 'page N of TOTAL' progress as it streams.
Why is client-side conversion better than server-based alternatives?
Server-based converters must accept your entire file upload, hold it in memory or on disk, process it in a shared queue, and stream the result back — which adds latency, imposes file-size caps, and means your document sits on someone else's infrastructure. MarkdownForge does the work on your own CPU with bounded, streaming memory usage, so there is no upload wait, no queue, no arbitrary size limit, and no third-party copy of your data. It also scales for free: every user brings their own compute.
Does the converter work offline, and is my data ever uploaded?
Every file-based conversion runs entirely on your device with zero uploads, so once the page has loaded it keeps working even if your connection drops. The single exception is the optional URL-to-Markdown feature, which must fetch the remote page's HTML through a stateless CORS proxy that stores nothing — no other feature makes a network request with your data.
Which file formats can I convert to Markdown?
You can convert HTML, Word DOCX, Excel/ODS spreadsheets, CSV/TSV data, live web page URLs, Evernote/XML exports, YAML, Jupyter notebooks (.ipynb), and PDF documents. Each format has a dedicated, SEO-friendly converter page with tailored options.