Acorn

What it is

Acorn is a lightweight and efficient ECMAScript parser written in JavaScript. It is designed to parse JavaScript code quickly and accurately, making it suitable for applications that require real-time parsing, such as code editors and linters. Acorn supports the latest ECMAScript standards and is highly configurable, allowing developers to customize its behavior to suit their specific needs. With no dependencies, Acorn is easy to integrate into existing projects and is maintained by a community of contributors.

Acorn's combination of speed, configurability, and no dependencies makes it uniquely suited for lightweight JavaScript parsing.

When it fits — and when it doesn’t

Known weaknesses

Each one links to the public issue, changelog or docs page it came from, where we have one.

1. 01

   Limited to JavaScript

   Primarily designed for ECMAScript parsing.

2. 02

   Requires manual configuration for advanced use cases

   Highly configurable nature means more setup for complex scenarios.

3. 03

   No built-in error recovery

   Focuses on speed and simplicity over error handling.

What it does well

• Lightweight with no dependencies

  The npm package has a dependency count of 0.

• High weekly downloads

  Over 254 million weekly downloads as of August 2026.

• Supports latest ECMAScript standards

  Regular updates and a large number of total versions (140).

• Highly configurable

  Allows customization of parsing behavior.

Pricing

Free tier

Yes

Paid from

—

Model

Flat rate

Enterprise plan

No

Pricing last confirmed Sep 30, 2026.