Convert documents to Markdown entirely offline on your Mac

7 August 2026 · Milldown team · All posts

Most “free PDF to Markdown” tools are websites. That means your contract, patient letter, or unpublished manuscript travels to someone else’s server, gets processed there, and lives in their logs for however long their retention policy says — if they have one. For a lot of documents, that’s simply not acceptable.

Who actually needs local conversion

• Legal — contracts, discovery documents, and anything privileged. Uploading to a third party can itself be a confidentiality problem.
• Healthcare — patient records and referral letters carry regulatory weight (HIPAA, GDPR) that a converter website’s terms of service won’t cover.
• Finance — deal documents, board papers, and anything price-sensitive.
• Journalists and researchers — source-provided documents where the metadata trail matters as much as the content.
• Anyone preparing documents for AI — ironically, the cleanest way to keep control is to do the conversion locally and decide afterwards exactly which text the model gets to see.

What “local” has to mean

“Private” and “secure” on a landing page mean nothing by themselves. A converter is local if — and only if — the file’s contents never leave your machine at any step:

1. Conversion runs on your hardware.Not “processed securely in the cloud.” On your Mac, by a process you can see in Activity Monitor.
2. OCR runs on-device too.Scanned PDFs are where many “local” tools quietly phone home, because cloud OCR is easier. Milldown uses Apple’s Vision framework — the same on-device OCR behind Live Text.
3. No account, no telemetry tied to file contents.A tool that needs a login has a server-side record that you converted something.
4. Honest refusals beat silent uploads.One example from our own audit: the open-source engine we bundle has an audio-transcription path that calls a cloud API. Rather than ship a privacy claim with an asterisk, Milldown refuses audio files outright.

How to verify it yourself

Don’t take a vendor’s word for it — including ours. Turn off Wi-Fi and convert a file: a genuinely local converter works identically with the network down. For a stronger check, run a monitor like Little Snitch during a conversion and watch for outbound connections. Milldown passes both, with one documented exception: converting a URL obviously fetches that URL. Our security page spells out exactly what does and doesn’t touch the network.

The workflow

Drop files into Milldown (or right-click in Finder → Services → Convert to Markdown). Review and edit the Markdown in the app, run the Clean Up pass if the source had page furniture, then copy or save. What leaves your Mac afterwards — a paste into Claude, a commit to a repo — is a decision you make with the converted text in front of you, not a side effect of using a converter.