Change API

Usage

Change API uses 1 API credit per domain that returns one or more technology changes.

Domains with no detected change history in the requested window do not consume API credits.

Introduction

The BuiltWith Change API returns technology additions and removals detected for one or more domains over a configurable time window.

Each change event includes the technology name, categories, tag, importance and an AI generated business explanation for why the change matters.

The general access method is as follows -
https://api.builtwith.com/change1/api.json?KEY=00000000-0000-0000-0000-000000000000&LOOKUP=[DOMAIN]

🤖 AI Agent Prompt

Reference https://api.builtwith.com/llms.txt and
https://raw.githubusercontent.com/builtwith/builtwith-ai-sdk/refs/heads/main/README.md
Add builtwith AI api to my app as a client. Make a call to the change API for the domain hotelscombined.com and show recent technology additions and removals

Authentication

You must provide your API key in each lookup.

Your API key is
00000000-0000-0000-0000-000000000000

Examples

Recent changes for a domain:

https://api.builtwith.com/change1/api.json?KEY=00000000-0000-0000-0000-000000000000&LOOKUP=hotelscombined.com

Changes since a natural language date:

https://api.builtwith.com/change1/api.json?KEY=00000000-0000-0000-0000-000000000000&LOOKUP=hotelscombined.com&SINCE=last+month

Multiple domains:

https://api.builtwith.com/change1/api.json?KEY=00000000-0000-0000-0000-000000000000&LOOKUP=hotelscombined.com,example.com

Reference

Parameters

Name	Examples	Required
`KEY`	`00000000-0000-0000-0000-000000000000`	Yes
`LOOKUP`	`hotelscombined.com` `hotelscombined.com,example.com`	Yes
`SINCE`	`last month` `2026-04-01`	No

Response Fields

Field	Description
`Results`	Array of lookup results, one item per requested domain.
`Lookup`	The root domain returned for the lookup.
`Changes.since_utc`	Start of the change detection window in UTC.
`Changes.last_checked_utc`	The most recent BuiltWith check date for the domain.
`Changes.summary`	Short generated summary of additions and removals.
`events.type`	`technology_added` or `technology_removed`
`events.technology`	Technology name.
`events.category`	BuiltWith technology categories.
`events.tag`	BuiltWith technology tag.
`events.first_seen_utc`	First seen timestamp for added events.
`events.last_seen_utc`	Last seen timestamp for removed events.
`events.importance`	`low`, `medium` or `high`
`events.why_this_matters`	AI generated explanation of the business significance of the change.

Example JSON

{
  "Results": [
    {
      "Lookup": "example.com",
      "Changes": {
        "since_utc": "2026-04-08T00:00:00Z",
        "last_checked_utc": "2026-05-08T00:00:00Z",
        "summary": "example.com added HubSpot and removed Marketo.",
        "events": [
          {
            "type": "technology_added",
            "technology": "HubSpot",
            "category": ["Marketing Automation"],
            "tag": "analytics",
            "first_seen_utc": "2026-05-02T00:00:00Z",
            "importance": "high",
            "why_this_matters": "Marketing automation adoption can indicate active investment in lead capture, nurturing and customer lifecycle programs."
          }
        ]
      }
    }
  ]
}

Error Codes

The Change API uses standard BuiltWith API error responses for invalid keys, exhausted credits, invalid domains and unsupported formats. See error codes.

Our standard terms cover the use all of our APIs.