Custom Extension Generator

Generate Any File Extension

Create a genuine file saved under any extension you choose — backed by a real format that opens in software.

1. Type your extension — Anything from .backup to .myformat.

2. Pick a base format — Determines the actual file structure and what software can open it.

3. Choose a size — From 10 KB to 100 MB.

4. Download — A genuine base-format file renamed to your extension.

Genuine file content

Not just renamed bytes — the internal structure matches the base format entirely.

Instant streaming

Generated on-the-fly. No storage, no upload, no account required.

Opens in real software

Any app that supports the base format will open the file correctly.

Step 1 — Your custom extension

Letters & numbers only, max 16 chars. Leading dot is optional.

Step 2 — Base format (determines file structure)

Genuine file — opens in software that supports ZIP Compressed Archive.

Step 3 — File sizeLimit: 100 MB

100% free · no signup · no ads · generated on-the-fly