Summarize with built-in AI

Thomas Steiner

Published: November 11, 2024, Last updated: July 30, 2025

Explainer	Web	Extensions	Chrome Status	Intent
MDN	Chrome 138	Chrome 138	View	Intent to Ship

You can offer your users the ability to distill lengthy articles, complex documents, or even lively chat conversations into concise and insightful summaries.

The Summarizer API can be used to generate different types of summaries in varied lengths and formats, such as sentences, paragraphs, bullet point lists, and more. We believe this API is useful in the following scenarios:

• Summarizing the key points of an article or a chat conversation.
• Suggesting titles and headings for articles.
• Creating a concise and informative summary of a lengthy text.
• Generating a teaser for a book based on a book review.

Get started

The Summarizer API is available from Chrome 138 stable.

Before you use this API, acknowledge Google's Generative AI Prohibited Uses Policy.

Run feature detection to see if the browser supports the Summarizer API.

if ('Summarizer' in self) {
  // The Summarizer API is supported.
}

Model download

The Summarizer API uses a model trained to generate high-quality summaries. The API is built into Chrome, and Gemini Nano is the model downloaded the first time a website uses this API.

To determine if the model is ready to use, call the asynchronous Summarizer.availability() function. If the response to availability() is downloadable, listen for download progress to inform the user of its progress, as it may take time.

const availability = await Summarizer.availability();

To trigger the model download and create the summarizer, check for user activation, then call the asynchronous Summarizer.create() function.

// Proceed to request batch or streaming summarization
const summarizer = await Summarizer.create({
  monitor(m) {
    m.addEventListener('downloadprogress', (e) => {
      console.log(`Downloaded ${e.loaded * 100}%`);
    });
  }
});

API functions

The create() function lets you configure a new summarizer object to your needs. It takes an optional options object with the following parameters:

• sharedContext: Additional shared context that can help the summarizer.
• type: The type of the summarization, with the allowed values key-points (default), tldr, teaser, and headline. See the following table for details.
• format: The format of the summarization, with the allowed values markdown (default) and plain-text.
• length: The length of the summarization, with the allowed values short, medium (default), and long. The meanings of these lengths vary depending on the type requested. For example, in Chrome's implementation, a short key-points summary consists of three bullet points, and a short summary is one sentence.

Once set, the parameters can't be changed. Create a new summarizer object if you need to make modifications to the parameters.

The following table demonstrates the different types of summaries and their corresponding lengths. The lengths represent the maximum possible value, as sometimes, the results can be shorter.

For example, you could initialize a summarizer to output a medium length of key points in Markdown.

const options = {
  sharedContext: 'This is a scientific article',
  type: 'key-points',
  format: 'markdown',
  length: 'medium',
  monitor(m) {
    m.addEventListener('downloadprogress', (e) => {
      console.log(`Downloaded ${e.loaded * 100}%`);
    });
  }
};

const availability = await Summarizer.availability();
if (availability === 'unavailable') {
  // The Summarizer API isn't usable.
  return;
}

// Check for user activation before creating the summarizer
if (navigator.userActivation.isActive) {
  const summarizer = await Summarizer.create(options);
}

Run the summarizer

There are two ways to run the summarizer: streaming and batch (non-streaming).

Batch summarization

With batch summarization, the model processes the input as a whole and then produces the output.

To get a batch summary, call the summarize() function. The first argument is the text that you want to summarize. The second, optional argument is an object with a context field. This field lets you add background details that might improve the summarization.

const longText = document.querySelector('article').innerHTML;
const summary = await summarizer.summarize(longText, {
  context: 'This article is intended for a tech-savvy audience.',
});

Streaming summarization

Streaming summarization offers results in real-time. The output updates continuously as the input is added and adjusted. To get a streaming summary, call summarizeStreaming() instead of summarize().

const longText = document.querySelector('article').innerHTML;
const stream = summarizer.summarizeStreaming(longText, {
  context: 'This article is intended for junior developers.',
});
for await (const chunk of stream) {
  console.log(chunk);
}

Demo

You can try the Summarizer API in the Summarizer API Playground.

Standardization effort

We're working to standardize the Summarizer API for cross-browser compatibility.

The Summarizer API and other Writing Assistance APIs have been adopted by the W3C WebML Working Group. We've asked asked Mozilla and WebKit for their standards positions.

Share feedback

We want to see what you're building with the Summarizer API. Share your websites and web applications with us on X, YouTube, and LinkedIn.

For feedback on Chrome's implementation, file a bug report or a feature request.