How to merge ZIP files
Combine multiple ZIP archives into one, with deterministic handling for files that share the same name.
Merging combines several archives into a single ZIP while keeping folder structures intact and resolving name collisions deterministically.
1. Add the archives
Select two or more ZIP files. They are listed in the order you will merge them, and you can drag to reorder. Order matters for the conflict strategy you choose.
2. Choose how collisions are handled
When two archives contain a file with the same name, the tool needs a deterministic policy:
- Rename automatically (default): report.pdf becomes report (1).pdf. Nothing is ever overwritten.
- Replace: the later archive's file wins and the earlier one is dropped.
- Keep first: the first archive's file wins and later duplicates are skipped.
- Keep both: duplicate names are kept as separate entries in the merged archive.
3. Merge and download
Click Merge ZIP. The combined archive is built in your browser and downloaded as merged.zip. Your source archives are never modified.
What merging preserves
Merging is a rebuild, so it preserves file contents exactly, plus folder hierarchy and entry timestamps. The ZIP container itself is reconstructed, which means byte-level metadata such as archive comments and extra fields may not carry over.
Frequently asked questions
What happens to files with the same name?
By default they are renamed automatically: report.pdf becomes report (1).pdf. You can also choose Replace, Keep first, or Keep both.
Does merging recompress my files?
Entries are rebuilt with standard DEFLATE compression. Already-stored entries remain stored, so compressed content is not degraded.