All

• Android - Build mobile apps for Android, a software stack for mobile devices.
• Gmail Atom Feeds - Offers a simple feed mechanism for reading your Gmail inbox or labels.
• Google Account Authentication - Get access into desktop or mobile applications.
• Google Analytics - Track total page views, unique visitors, and AdWords conversions on your site.
• Google App Engine - Run your web applications on Google's infrastructure.
• Google Base Data API - Manage Google Base content programmatically.
• Google Chart API - Dynamically embed charts in your webpage.
• Google Checkout API - Start selling on your website.
• Google Coupon Feeds - Provide coupon listings that are included in Google search results.
• Google Desktop Gadget API - Write powerful, visually appealing gadgets for millions of Google Desktop users around the world.
• Google Mashup Editor - Quickly write code for simple web applications and mashups.
• Google Notebook Data API - Enables your apps to view stored data as Google Data API feeds.
• Google Safe Browsing APIs - Download lists of suspected phishing and malware URLs.
• Google Themes API - Design a dynamic theme for the iGoogle homepage.
• Protocol Buffers - Serialize structured data in a language-neutral, platform-neutral, extensible way.

Ads

• Google AdSense API  - Generate revenue for you and your users by placing ads on your website.
• Google AdSense for Audio API - Incorporate AdSense for Audio into your broadcast system.
• Google AdWords API - Automate and streamline your campaign management activities.

AJAX

• Google AJAX APIs - Implement rich, dynamic web sites entirely in JavaScript and HTML.
• Google AJAX Feed API - Easily mash up public feeds using JavaScript.
• Google AJAX Language API - Easily translate and detect multiple languages using JavaScript.
• Google AJAX Search API  - Put a Google Search box and results on your own site. 
• Google Book Search APIs -  Integrate Google Book Search content into your website or application. 
• Google Earth API - Embed Google Earth into your web page.
• Google Maps API - Integrate Google's interactive maps with data on your site. 
• Google Visualization API - Create visualizations and reporting applications that access structured data in a common format. 

Browser

• Chromium - Contribute to the open source project behind Google Chrome.
• Gears - Enable web applications to work offline, from your desktop PC or your mobile device.
• Google Web Toolkit - Build AJAX apps in the Java language.
• V8 - Google's high performance, open source, JavaScript engine.

Geo

• Google Mapplets - Build mini-applications to embed within the Google Maps site.
• Google Maps API For Flash - Integrate Google Maps in Flash applications.
• Google SketchUp Ruby API - Extend Google SketchUp with Ruby.
• Google Static Maps API - Embed a Google Maps image on your webpage without requiring JavaScript or any dynamic page loading.
• Google Transit Feed Specification - Provide public transit route and schedule information for Google Maps and more.
• KML - Create and share content with Google Earth, Maps, and Maps for mobile.

Product APIs

• Blogger Data API - Enable your apps to view and update Blogger content.
• Feedburner APIs - Interact with FeedBurner's feed management and awareness-generating capabilities.
• Gadgets API - Build mini-apps that run on multiple sites including iGoogle, Google Desktop, or any webpage.
• Google Apps APIs - Provides domain administration for Premier and Education Edition customers.
• Google Calendar APIs and Tools - Create and manage events, calendars, and gadgets for Google Calendar. 
• Google Data APIs - A simple, standard protocol for reading and writing data on the web.
• Google Documents List Data API - Enable your apps to view and update your list of Google Documents. 
• Google Finance Data API - View and update Finance content in the form of Google Data API feeds.
• Google Health API - Manage your personal health information with Google.
• Google Spreadsheets Data API - Enable your apps to view and update Google Spreadsheets content.
• Google Talk for Developers - Connect your client or network to the Google Talk network, add chatback, or customize the Google Talk gadget.
• Google Toolbar API - Lets you create custom buttons for the Google Toolbar.
• iGoogle Developer Home - Build and test your gadget in the new sandbox for iGoogle.
• Orkut Developer Home - Create social applications for the millions of global Orkut users.
• Picasa APIs - Create custom buttons and upload files to 3rd party service.
• YouTube APIs - Integrate YouTube videos into your website or application.

Search

• Google Code Search - Search public source code.
• Google Code Search Data API - Enable your apps to view data from Code Search.
• Google Custom Search API - Create a custom search engine for your website or a collection of websites. 
• Google Desktop Search APIs - Put desktop search support into your apps, or extend Google Desktop to search more file types.
• Google Search Appliance APIs - Enables complete control over enterprise search results.
• Google Sitemaps - Enables Google to quickly crawl your website.
• Google Webmaster Tools Data API - View and update site information and Sitemaps in the form of feeds.
  
• Subscribed Links - Define search keywords that trigger custom search results.

Social

• Google Contacts Data API - Allow your apps to view and update user contacts.
• Google Friend Connect - Grow website traffic with easy-to-add social features.
• OpenSocial - Build social applications that work across many websites.
• Social Graph API - Enable users to quickly add their public social connections to your site.