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

Quick facts

Extension.wasm

File typeWebAssembly Module

MIME typeapplication/wasm

CategoryData & Text

Charset—

CompressibleYes

Format familywasm

What is .wasm

What is a .wasm file?

A .wasm file is a WebAssembly Module — Compiled WebAssembly binary module.

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

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

How to open .wasm files

Use Chrome or Node.js to open and edit .wasm 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/wasm

Common software that reads/writes .wasm:

ChromeNode.jswasm-tools

Relation chain

.wasmextension of

format

wasmserved as

mime type

application/wasmsent via header

http header

Related extensions

Related MIME types

Common uses

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

How to edit .wasm files

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

How to create .wasm files

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

Frequently asked questions

What programs can open .wasm files?

Common options include Chrome, Node.js, wasm-tools. You can also open many of these files with built-in viewers or a browser.

How do I create a .wasm file?

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

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

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

Sources & standards

Updated 2026-08-18

Explore this reference

What is a .wasm file?

What programs can open .wasm files?

How do I create a .wasm file?

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

Related extensions

Related MIME types

Related headers

Related methods

Related status codes