Check PNG Interlacing
Scan image headers to identify if the file is optimized for progressive rendering. Runs entirely in your browser, so your data never leaves your device.
Drop an image here
or browse your files
Accepts PNG · everything is processed on your device, nothing is uploaded
Your PNG files never leave this tab
Check PNG Interlacing is JavaScript that your browser has already downloaded, and it does the whole job on your own machine. On a normal site, 200 photos straight off a camera means 1.6 GB uploaded, a wait in somebody's queue, and 240 MB downloaded again. Here it means 0 bytes up and 0 bytes down.
- No upload
- No file size limit
- Works offline once loaded
- Nothing stored or logged
How to use Check PNG Interlacing
- 1. Drop in the PNG file. Add the image you want to inspect. No editing happens here, so the original file is only read, never modified.
- 2. Let the tool read the header. It parses the PNG's IHDR chunk and checks the interlace method field, which is either 0 for no interlacing or 1 for Adam7.
- 3. Copy the result. The output reports whether the file is Interlaced (Adam7) or Not interlaced, so you know immediately how the file was encoded.
When to use Check PNG Interlacing
Check PNG Interlacing reads a file's header to tell you whether it uses Adam7 progressive rendering or standard top-to-bottom encoding. It is a quick diagnostic for anyone debugging load behavior or auditing how assets were exported.
- Debugging a slow perceived load. A page image seems to appear all at once rather than sharpening progressively, and checking the file confirms whether it was ever interlaced in the first place.
- Auditing exported assets. You inherited a folder of PNGs from an old CMS and want to know which ones were saved with interlacing before deciding whether to re-export them.
- Verifying an export setting. You set an image tool to export with Adam7 interlacing enabled and want to confirm the header actually reflects that choice before shipping the asset.
Examples
Detect Adam7 interlacing
Input
photo.png
Output
Interlaced (Adam7)
About the Check PNG Interlacing tool
Check PNG Interlacing does its work locally, right in the browser. Scan image headers to identify if the file is optimized for progressive rendering. There is no upload step, no queue and no account, and your data never travels over the network.
It belongs to the PNG Tools collection on EditSafely, a set of 108 small, focused PNG utilities that share the same instant, private workspace.
There is nothing to configure. Provide the input and the result appears on its own. A worked example further down the page shows exactly what the tool produces for a real input.
Running locally also makes the tool fast and dependable: results appear as you type or drop a file, there is no server outage that can take it down mid-task, and confidential data can be processed without a second thought.
Frequently asked questions
Does Check PNG Interlacing cost anything?
Yes, it is completely free. All 2,676 tools on EditSafely work without an account, a subscription or usage limits.
Are my files uploaded to a server?
No data leaves your device. The whole tool is JavaScript that runs inside your browser tab, so there is no upload, no server-side processing and no log of what you did. If you disconnect from the internet after the page loads, it keeps working.
Which files does Check PNG Interlacing accept?
It accepts PNG images. There is no file size cap imposed by a server; very large files are limited only by your device's memory.
Do I need to sign up or install anything?
Nothing to install and no account needed. Open the page in any up-to-date browser, including on a phone or tablet, and the tool is ready.
How do I use the result?
The output panel has a one-click copy button, and you can keep refining the input while you work; the result updates in place as you type.