I work on OnePassApps, so this is our own product, and every sentence quoted below was read off our own live pages in one browser session today.
"Does an online file converter upload my file?" is the question that decides whether you trust a tool with a photo, a contract or a customer list. The answer depends on the converter. Here is our own version of the check, because we build one of these tools and we would rather show you the wording than ask you to take it on faith.
What we measured
One Chrome session, signed out, one build, seven studio routes, one DOM text sweep per route on 4 November 2026. The sweep collected each page's own description line, its footer line and any privacy or limit sentence the page carries. No file was dropped and no tool was run in this pass - it read the pages only.
| Studio | The sentences the page carries |
|---|---|
| Image | "Convert, compress, resize, crop and clean images in your browser. Nothing leaves this tab." / "Processing stays in this browser." |
| Audio | "Convert, compress, trim and extract audio locally. Your media stays in this browser tab." / "Processing stays in this browser." |
| Files | "Create archives, inspect local ZIP files, compare hashes, rename copies and join split parts. Your files stay in this tab." / "Nothing leaves this tab." / "Processing stays in this browser." |
| Text | "Count, clean, compare and convert text locally. Your content stays in this browser tab." / "Nothing leaves this tab." / "Processing stays in this browser." |
| Data | "View and transform CSV, JSON, and YAML locally in this browser tab." / "Nothing leaves this tab." / "Processing stays in this browser." |
| Icons | "Create icons and favicon assets on this device. Files stay in your active browser tab." / "Processing stays in this browser." |
| Colour | "Pick, convert, compare and sample colours on this device. Your values and selected images stay in this browser tab." / "Nothing leaves this tab." |
Five things that came out of it
1. Every studio promises something, and the promise changes seven times. "Nothing leaves this tab." / "Your files stay in this tab." / "Your content stays in this browser tab." / "Your media stays in this browser tab." / "Files stay in your active browser tab." / "Your values and selected images stay in this browser tab." / "Any files · up to 500 and 256 MiB in total · stays on this device". Three different scopes turn up - this tab, this browser, this device - and they are not the same promise. A tool that keeps the file in the tab can still phone home for a licence check. A tool that keeps it on the device can still write a log somewhere else.
2. One studio never says "Nothing leaves this tab." The Icon Studio does not use the phrase. It says "Files stay in your active browser tab." - a narrower claim, because it is about the file rather than about the page. If you were checking a converter for that exact wording, the Icon Studio would fail the grep.
3. Two studios say two different things on one page. The File Studio's description says "Your files stay in this tab." and its footer says "Nothing leaves this tab." The Text Studio's description says "Your content stays in this browser tab." and its footer says "Nothing leaves this tab." Nothing contradictory in practice, but you cannot tell which scope the tool means if you read only the first line.
4. The strongest wording is hiding in a size limit. Only the Text Studio's limit line says "nothing is uploaded": ".txt, .md, .csv and other text up to 8 MiB · or paste it in Input text · nothing is uploaded". Its own privacy sentence only says "Your content stays in this browser tab." The File Studio's limit line says "stays on this device". The Data Studio's limit line - "CSV, TSV, JSON or YAML · up to 20 MiB · or paste rows in Source" - carries no promise at all.
5. Six studios state their limits. The seventh does not. The Image Studio says "JPEG, PNG or WebP · up to 25 MiB and 25 megapixels". The Audio Studio says "MP3, WAV, M4A, AAC, OGG, Opus, FLAC or WebM · up to 32 MiB and 45 minutes". The Text Studio says 8 MiB, the Data Studio 20 MiB, the Icons Studio "SVG up to 5 MiB and 25,000 elements", the File Studio 500 files and 256 MiB. The Colour Studio carries no size or type line on the page, and we did not measure what it accepts in this pass, so we are not claiming anything about it. (We wrote the caps up properly in that post.)
How to check any converter, including this one
- Read the promise, then read the scope. "In this tab", "in this browser" and "on this device" are three different claims.
- Open DevTools - Network, drop a file, and look for a POST. A converter that uploads sends your bytes somewhere, and the request shows it.
- Turn the network off and try the tool. We tested ours with the connection cut on 4 November: the Text Studio still converted a line of text and the page said "You are offline. Tools on this device keep working; live apps refresh when you are back." That test is in our offline test. The wider picture - what each of the seven studios actually sends while you work - is in the network audit.
- Check the limits before you trust it with a big file.
- If it uploads, the file reached a server. Whatever the page says about deletion, the file has been somewhere that is not your laptop.
The limits of this pass
- Signed out, one browser, one build, one day, English only, desktop only.
- These are the words the pages carry. A sentence is not an audit of the code - the two tests linked above are the behavioural checks, and they are separate from this one.
- The sentence counts are distinct strings each page carried in this sweep; some pages repeat one of their sentences in more than one place.
- We ran no tool in this pass, and we did not measure the Colour Studio's accepted file types.
Try it
The seven studios sit under one membership, and the standard plan is free right now with no card: https://app.onepassapps.com/studios/image?utm_source=devto&utm_medium=post&utm_campaign=privacy-wording&utm_content=studio-link. The app guides for the two hosted apps are here: https://app.onepassapps.com/guides?utm_source=devto&utm_medium=post&utm_campaign=privacy-wording&utm_content=guides-link.
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