---
title: ".bak file — what it is and how to open it"
description: "A .bak file is a Backup File. A copy of another file, saved before it changed — the extension says nothing about the contents. How to open one on Windows, macOS and Linux, and what to convert it to."
url: https://atoneplace.net/file/bak/
site: "At One Place"
---

# .bak files

**.bak file: Backup File**

A copy of another file, saved before it changed — the extension says nothing about the contents.

## What opens a .bak file

- **Windows:** Rename to the original extension, then use that program, Notepad (built in — to check if it is text)
- **macOS:** Rename to the original extension, then use that program, TextEdit (built in — to check)
- **Linux:** Rename to the original extension, then use that program, file (to identify it)

## What a .bak file is

Programs create .bak files automatically before overwriting something, so a .bak is whatever the original was: a document, a database, a config file. To use one, remove the .bak from the name and open it with the program that made it. Windows hides known extensions by default, so a file that looks like "notes.docx" may actually be "notes.docx.bak" — turn on file extensions in File Explorer before renaming.

## Details

- **Extension:** .bak
- **Full name:** Backup File
- **Category:** Data
- **Created by:** Various
- **Format:** Binary

## Common questions

### How do I open a .bak file?

On Windows use Rename to the original extension, then use that program; on macOS use Rename to the original extension, then use that program; on Linux use Rename to the original extension, then use that program. A copy of another file, saved before it changed — the extension says nothing about the contents.

### What is a .bak file?

Backup File. Programs create .bak files automatically before overwriting something, so a .bak is whatever the original was: a document, a database, a config file. To use one, remove the .bak from the name and open it with the program that made it.

## Related pages

- [.csv — Comma-Separated Values](https://atoneplace.net/file/csv/)
- [.json — JavaScript Object Notation](https://atoneplace.net/file/json/)
- [.xml — Extensible Markup Language](https://atoneplace.net/file/xml/)
- [.yaml — YAML Data File](https://atoneplace.net/file/yaml/)
- [.log — Log File](https://atoneplace.net/file/log/)
- [.torrent — BitTorrent Metainfo File](https://atoneplace.net/file/torrent/)
- [.dat — Generic Data File](https://atoneplace.net/file/dat/)
- [.vcf — vCard Contact File](https://atoneplace.net/file/vcf/)
- [.sql — SQL Script](https://atoneplace.net/file/sql/)
- [.ics — iCalendar Event](https://atoneplace.net/file/ics/)
- [.sqlite — SQLite Database](https://atoneplace.net/file/sqlite/)
- [.db — Generic Database File](https://atoneplace.net/file/db/)

## Sources

- Media Types Registry — IANA (https://www.iana.org/assignments/media-types/)
- Official vendor product documentation — At One Place (/about/)