APIs are a great way of developing custom SEO applications.   By tying together these building blocks, you can quickly and easily develop tools such as our example free SEO site comparison tool.

Here’s our Top 10 list of SEO APIs:

 

 

#1 SEOMoz API

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SEOMoz – a leading SEO Software company with years of SEO consulting background have developed their own link graph of the web – known as Linkscape.    They offer free access to this link graph via their API.   Offering access to back links, page authority and page ranking statistics, SEOMoz is number one in our top ten list.

 

 

#2 Alchemy Keyword API

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Alchemy provide an advanced API based around term/keyword extraction.   Using advanced linguistic algorithms, the API is able to extract common phrases and is even able to infer the topic of the content.

 

 

#3 Google Search API

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As the #1 search engine, Google provide numerous APIs to most of their online tools.   The AJAC Search API provides access to Web Search, Local Search and Multimedia Search.

 

 

#4 Yahoo Search API

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Always popular in SEO, the Yahoo Site Explorer tool provides reliable backlink data on websites.   You can access this data via the Yahoo API.  The future of this tool could be limited due to the integration with the Microsoft Bing engine.

 

 

#5 Bing API

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Microsoft’s search engine is growing in popularity and becoming increasingly advanced.   Microsoft have realised the potential of APIs by providing access to Web, image, InstantAnswer, Phonebook, RelatedSearch, Spell and more.

 

 

#6 Majestic SEO API

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Another link graph of the web is provided by Majestic SEO.   Majestic have used their own crawling technology to provide an extensive data.   Through the free API you can gain access to the number of referring domains and the number of external backlinks to a site.

 

 

#7 Twitter API

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Twitter, the popular Social Networking application provide extensive search access to their data and trends via free API calls.

 

 

#8 Compete API

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Compete, a web analytics company, provide free API access to their site traffic and history statistics.   Compete also provide their own trust data based on surveys and analytics tracking.

 

 

#9 Backtype API

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Backtype indexes comments from blogs, social networking and other social media.   You can access the resulting data via their free API.

 

 

#10 Amazon Alexa API

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Alexa have been analysing site traffic for years via their free browser toolbar plug-in.   They’ve teamed with Amazon to give API access to this data.   Unfortunately, unlike the above APIs, access isn’t free however calls are very cheap.