Support
Help with the DocSlim app and online tools
I made DocSlim because I got tired of form portals saying "photo must be under 50 KB" and then rejecting everything I uploaded. If something isn't working for you, I want to know.
Online tools
What's the difference between the website and the app?
Both are free and cover the main compress, resize, scan and PDF tools. The online tools work in any browser on any phone or computer. The iPhone app adds live camera edge detection while scanning, Face ID lock, and works fully offline.
The online tool can't open my photo.
JPG, PNG and WebP work in every modern browser. HEIC photos from an iPhone open in Safari but not in every other browser. If a photo won't open, share it to yourself as a JPG or take a screenshot of it, then try again.
The camera doesn't open when I tap Take a photo.
On a phone, your browser asks to use the camera the first time. If you said no, allow it in the browser's site settings. On a computer, choose a photo of the document instead.
Where are files from Save to My files kept?
Only in the browser you saved them from, on that device. They aren't uploaded. Clearing the browser's site data or using a different browser means you won't see them. On a shared computer, delete them from My files before you leave.
Can I use the website offline?
Yes, after your first visit. The tools are saved by your browser, so they keep working without internet. On a phone, use "Add to Home Screen" to open DocSlim like an app.
Merge PDF says it can't open my file.
The file is probably password-protected. Open it, save or print it as a new PDF without a password, and add that copy instead.
iPhone app
I set 50 KB but the portal still says the file is too big.
Some portals count 1 KB as 1000 bytes and some as 1024. DocSlim always aims for the smaller number, so the file should pass on both. If it still fails, the portal might also want exact pixel dimensions. Turn on exact dimensions, or pick a preset, and try again.
The file came out much smaller than the size I typed.
That's normal for small images like signatures. A 140×60 signature is only a few KB even at full quality, so there's nothing left to compress. It's still under the limit, which is what matters.
The portal says the file is too small.
A few forms want something like "between 20 KB and 50 KB". Type the upper number (50) as the target. DocSlim gets as close to it as it can, which almost always puts you inside the range.
I forgot a page. Do I have to scan everything again?
No. Open the Files tab, tap the PDF, then tap "Add pages". You can scan more, pick photos, or add another PDF. Tap Save and it updates the same file.
Can I change a file's name?
Yes. Type a name before saving, or in the Files tab swipe left on a file and tap Rename. DocSlim swaps spaces for underscores and drops symbols, because a lot of upload portals don't accept them.
Where are my files kept?
Only on your device, inside the app. Nothing is uploaded anywhere. If you delete the app, the files go with it, so share or save anything important to the Files app or iCloud Drive first.
Why can't I select text in a compressed PDF?
To shrink a PDF, DocSlim saves each page as an image. Portals only need to see the page, so this doesn't matter for uploads, but the text in the compressed copy can't be selected or searched.
Is DocSlim free?
Yes. Every tool is free to use, with no ads, no account and no watermark on your files.
Can I lock the app?
Yes. In the app, go to Settings and turn on "Lock with Face ID". DocSlim then locks whenever you leave it. If Face ID doesn't recognise you, you can use your iPhone passcode instead.