Can I convert PNG to ICO without an internet connection?
Yes, conversion and download worked in my test after I opened the page online and kept it open; a fresh offline browser context could not load the page.
Keep the loaded page open.
Load the page before going offline
- Open the PNG to ICO converter while you are online.
- Keep the page open. In my test, I selected the PNG after switching the browser context offline.
- Choose your sizes, click Create ICO, and save the download.
Can you reload the tab offline? I did not test that, or opening the page from a previously cached browser profile.
What I actually ran
I used headless Chrome 156.0.8078.80 on November 6, 2026. The live converter returned HTTP 200 before I switched its browser context offline.
After the switch, I selected the published 64 × 32 wide PNG from the local disk. I kept all seven sizes checked, clicked Create ICO, and saved the download. The browser context remained offline throughout.
| Check | Observed result |
|---|---|
| Converter page loaded online | HTTP 200 |
| PNG selected after the offline switch | The converter accepted the local file |
| Create ICO while offline | The ready message reported seven frames and 4,671 bytes |
| Download while offline | The ICO was saved to disk and measured 4,671 bytes |
| Read the saved ICO directory | Seven entries: 16×16, 24×24, 32×32, 48×48, 64×64, 128×128, and 256×256 |
| Open the page in a separate, fresh offline context | Navigation failed with net::ERR_INTERNET_DISCONNECTED |
Did the download produce a file? Yes. I checked the saved ICO directory and found all seven entries.
What remains untested
I set the browser contexts offline. The Windows machine stayed connected to its network. This was an automated Chrome test, not a manual whole-machine disconnect.
I did not test mobile browsers, other browser versions, offline reloads, or how long an already-open page remains usable. The byte count describes this sample only.
If the page has closed, reconnect and load it again before converting another file.
For other file and download checks, see the conversion guides.