What Is a .map File? .map Format, MIME & How to Open

Quick facts

Extension.map

File typeSource Map File

MIME typeapplication/json

CategoryData & Text

CharsetUTF-8

CompressibleYes

Format familyjson

What is .map

What is a .map file?

A .map file is a Source Map File — JSON source map linking minified code to sources.

In the mime-db registry it maps to application/json with UTF-8 encoding, and it is marked as compressible. When serving .map over HTTP, set the Content-Type header as shown in Developer info below.

Related entities: it maps to application/json — and is delivered over HTTP via the Content-Type header.

How to open .map files

Use Chrome DevTools or VS Code to open and edit .map files.
Any text editor (Notepad, VS Code) can inspect the raw content as text.

Developer info

When served over HTTP, responses should set the following header:

Content-Type: application/json; charset=utf-8

Common software that reads/writes .map:

Chrome DevToolsVS Code

Relation chain

.mapextension of

format

jsonserved as

mime type

application/jsonsent via header

http header

Related extensions

JSON5 Configuration File

Related MIME types

application/json

.json .map

Common uses

Configuration files
Data interchange between systems
API request and response payloads
Logs and data exports

How to edit .map files

Open the file with Chrome DevTools, make your changes and save.
Most editors preserve the original formatting and encoding — avoid changing the charset.

How to create .map files

Create a new file and save it with the .map extension, or export this format from Chrome DevTools.

Frequently asked questions

What programs can open .map files?

Common options include Chrome DevTools, VS Code. You can also open many of these files with built-in viewers or a browser.

How do I create a .map file?

Create a new file in any text editor or the app that owns the format and save it with the .map extension.

What is the relationship between .map and the application/json MIME type?

application/json is the media type identifier used for .map files during network transfer (for example in the HTTP Content-Type header).

Sources & standards

Updated 2026-09-13

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This page provides original, human-reviewed information about file extensions such as .map, the File Extension Reference and related concepts. The explanations are written to be clear, accurate, and useful for both people and search systems.

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