The Best File Converters for Privacy: Which Tools Keep Your Files Local?
Quick answer: If privacy is the deciding factor, the converters that never upload anything are the ones worth installing: Squoosh for images in a browser tab, XnConvert for large desktop batches, Pandoc for documents on the command line, and an on-device mobile app for whatever is already on your phone. Cloud services such as CloudConvert, Zamzar and Convertio are still the better pick when you need a format pair nothing local supports, or when you are on a machine where you cannot install software — they publish real deletion and encryption policies, but your file does exist on their infrastructure for the length of the job. Match the tool to the sensitivity of the file, not to whichever site ranks first.
Every file converter answers the same question differently: where does the work happen? Some do it on your own processor, where the file never moves. Others upload your file, convert it on a server farm, and hand back a download link. Both approaches are legitimate. Only one of them is a privacy decision you can make once and stop thinking about.
This guide compares seven converters on four things you can actually check: platforms, how they charge, whether they work without an internet connection, and whether you have to create an account. One of them — LocalConvert — is ours, and it is labelled as such. Everything else comes from the makers' own documentation, linked at the bottom.
What "private" actually means for a converter
"Privacy-focused" is a marketing phrase, so it helps to break it into properties you can verify:
- Where processing happens. On your device, in your browser tab, or on a remote server. This is the property that matters most, and reputable tools state it plainly.
- What is retained, and for how long. Cloud services that take privacy seriously publish deletion windows. Vague answers here are the warning sign.
- Whether an account is needed. An account links every conversion you make to an identity and an email address.
- What the tool sends about you. Analytics on a converter's own web page is not the same as uploading your file, but it is worth knowing about.
Our longer explainer on whether online file converters are safe covers the threat model in detail. This page is about picking a tool.
The comparison at a glance
| Tool | Platforms | Price model | Works offline | Account required |
|---|---|---|---|---|
| Squoosh | Any modern browser | Free, open source (Google Chrome Labs) | Compression runs locally in the tab; the page itself is loaded from the web | No |
| XnConvert | Windows, macOS, Linux | Free for private, educational and non-profit use; licence required inside a company | Yes — runs entirely on your machine | No |
| Pandoc | Windows, macOS, Linux (command line) | Free and open source (GPL v2) | Yes — a local binary | No |
| CloudConvert | Web, plus an API | Free tier of 10 conversion credits/day; packages and subscriptions above that | No — cloud processing | Yes, for the free daily credits (no credit card) |
| Zamzar | Web | Free: 2 files per 24 hours, up to 50 MB; paid plans raise both limits | No — cloud processing | No for the free service |
| Convertio | Web | Basic conversions free; sign-up unlocks larger uploads and faster processing | No — conversion happens on remote servers | Not for basic conversions |
| LocalConvert (ours) | iPhone, iPad (iOS 16+) | Free | Yes — 100% on-device, no internet required | No |
Squoosh — proof that browsers can do this locally
Squoosh is an open-source image compression web app from Google Chrome Labs. Its documentation states the point directly: Squoosh does not send your image to a server, and all image compression processes locally. It compiles codecs to WebAssembly and runs them inside your tab, which is why it can offer a live side-by-side quality slider across JPEG, PNG, WebP, AVIF and others.
Strengths: nothing to install, genuinely local processing, excellent format coverage for images, and a visual comparison view that most converters lack. Worth knowing for completeness: the project's README notes the app uses Google Analytics for basic visitor metrics and compression statistics — that is page analytics, not your image.
When it is the better pick: you want to see exactly what a compression setting costs you visually, on a computer, without installing anything. For a single image and a careful eye, it is the best tool here.
XnConvert — the local batch engine
XnConvert from the XnView team converts thousands of images in one pass, across more than 500 formats, on Windows, macOS and Linux — including HEIC/HEIF, AVIF, JPEG XL, camera RAW, PSD and PDF. It chains up to 80 actions in a single run: resize, crop, rotate, watermark, adjust colours, and strip or edit metadata. Everything runs on your own machine, with no upload, no file-size limit, and no watermark on the result.
It is free for private, educational and non-profit use; a licence is required for use inside a company, which is a fair deal and clearly stated.
When it is the better pick: anything involving a folder rather than a file. If you need to convert and strip metadata from 4,000 photos on a Linux workstation, stop reading and install XnConvert.
Pandoc — documents, done properly
Pandoc is the universal document converter: a free, open-source command-line tool licensed under GPL v2, running on Windows, macOS and Linux. It converts between Markdown variants, Word documents, LaTeX, EPUB, PowerPoint, Jupyter notebooks, MediaWiki markup, OpenDocument and many more, and can produce PDF output.
Strengths: unmatched document fidelity, scriptable, entirely local, and permanently free. The obvious cost is the interface — it is a terminal command, not a drag-and-drop window, and that rules it out for a lot of people.
When it is the better pick: document conversion of any complexity, especially anything repeatable. A one-line Pandoc command replaces an entire category of "convert DOCX to Markdown online" websites, and no confidential draft ever leaves your laptop.
CloudConvert — the cloud service that documents itself
CloudConvert is a web service and API covering a very wide format range. Its free plan includes 10 conversion credits per day with a daily reset, no credit card required at sign-up, a 1 GB file-size cap, and up to five concurrent tasks.
Credit where it is due on transparency: CloudConvert states that all transfers are SSL encrypted, that files are kept only for processing and deleted immediately afterwards, that it is a German company committing to GDPR with a data processing agreement on request, and that parent company Lunaweb GmbH holds ISO 27001 certification from TÜV Süd, with ISO 27001 certified cloud providers and data centres.
When it is the better pick: a format pair no local tool handles, an automated pipeline that needs an API, or a managed work laptop where you cannot install anything. Those are genuine reasons, and this is the cloud converter we would reach for. The trade-off remains structural rather than a criticism: for the length of the job, a complete copy of your file exists on infrastructure you do not operate.
Zamzar — no account, no installation
Zamzar is one of the oldest names in online conversion and supports thousands of formats across documents, images, audio, video, e-books, CAD and archives. No account is needed to start. The free service accepts files up to 50 MB and allows up to two file conversions in any 24-hour period; converted files are securely stored for a maximum of 24 hours so you have time to download them, while originals from a failed conversion are kept up to seven days. Paid plans raise the size cap and remove the daily limit.
When it is the better pick: one unusual file, on a computer that is not yours, when you do not want to hand over an email address. The two-a-day ceiling makes it unsuitable as a daily driver, and Zamzar publishes that limit openly rather than burying it.
Convertio — the fastest path to one conversion
Convertio is a browser-based converter with a 1 GB maximum file size. Basic conversions are free, and signing up unlocks larger uploads and faster processing. The service is explicit that conversion happens on remote servers, and that uploaded files are deleted immediately after conversion with results purged from servers within 24 hours automatically.
When it is the better pick: you need one file converted right now, in a browser, with the least possible friction, and the file is not sensitive. That is a real use case and Convertio serves it well.
LocalConvert — full disclosure: we make this one
LocalConvert is our own iPhone and iPad app, so read this as the developer describing his own product. It performs 24+ format conversions entirely on the device, with no internet connection required: PNG ⇄ JPG, PNG ⇄ WebP, JPG ⇄ WebP, HEIC → JPG and HEIC → PNG; images into a single PDF and pages back out of one; ZIP creation and extraction; CSV ⇄ JSON, XML ⇄ JSON, YAML ⇄ JSON, JSON minify/beautify; Markdown → HTML and back; plus an EXIF remover that strips location, camera information and timestamps. There are no uploads, no analytics, no tracking, no accounts and no file-size limits. It is free on the App Store and needs iOS 16 or later.
Where it fits: files that are already on your phone — the photo of a document, the receipt, the PDF an office sent you. Where it does not: if your files live on a desktop, XnConvert and Pandoc are simply better tools for that job, and we would send you to them without hesitation. If you need a format pair we do not support, CloudConvert will convert it and delete it afterwards. And if you are on someone else's computer with one harmless file, Zamzar will do it without even asking who you are.
How we picked, and what we refuse to publish: every claim in the table comes from the maker's own documentation or store listing, checked in August 2026 and linked below. You will find no star ratings, no download counts, and no overall "winner" here. Free-tier limits on web services change frequently — verify current limits before relying on them — and the right converter depends far more on where your files are than on any score we could invent.
A simple rule for choosing
- Would you email this file to a stranger? If no, convert it locally — on your phone, your laptop, or in a browser tab that does the work in WebAssembly.
- Is it a folder rather than a file? Desktop batch tools win every time.
- Is it a document with structure worth preserving? Pandoc.
- Is it an odd format, on a machine you do not control? A reputable cloud service with a published deletion policy.
The formats are commodities; every tool here produces a valid JPG or PDF. What differs is the number of copies of your file that exist afterwards, and where they live.
How LocalConvert helps
LocalConvert runs 24+ conversions entirely on your iPhone or iPad — images, PDFs, ZIP archives, and data formats — with no uploads, no internet connection required, no analytics or tracking, and no file size limits. It can also strip EXIF metadata before you share. Free on the App Store, iOS 16+.
Get LocalConvert freeSources
- Squoosh — project README (Google Chrome Labs): local processing, no image sent to a server, Google Analytics for visitor metrics
- XnView — XnConvert and batch image converter: platforms, 500+ formats, 80 chained actions, licence terms
- Pandoc — project repository: GPL v2, universal document conversion, command-line tool, cross-platform
- CloudConvert — pricing and security: free daily credits, file-size cap, SSL, immediate deletion, GDPR, ISO 27001
- Zamzar FAQ: 50 MB and 2 files per 24 hours free, no account, 24-hour retention
- Convertio: 1 GB limit, server-side conversion, deletion policy, sign-up benefits
- LocalConvert facts: our own App Store listing and app documentation.