There are two main types of Instant Answers you can develop: Goodies, and Spice.
The difference comes down to a simple question: do you need to retrieve data from a third party API?
Goodies do not retrieve data from a third party API. Goodies provide their results entirely through server-side code. They may use a static data file stored on DuckDuckGo's server, but they do not call external resources.
Learn how to make a Goodie with these walkthroughs:
Cheat Sheets are a subset of Goodies. Learn to make a cheat sheet.
You can see examples of Goodies by filtering on the Instant Answer Directory.
Spices retrieve data from third party APIs. Spices provide their results via one or more calls to external endpoints. You can learn more about how this works here.
Learn how to make a Spice with these walkthroughs:
You can see examples of Spices by filtering on the Instant Answer Directory.
Fatheads are key-value Instant Answers backed by a database on DuckDuckGo's servers. The keys of the database are typically words or phrases, and they are also used as the triggers for the Instant Answer. When a database key is queried, the corresponding row from the database is returned, which is typically a paragraph of text.
For more on Fathead Instant Answers, see the Fathead overview.
Longtails are database-backed, full text search, Instant Answers. For every query DuckDuckGo receives, each Longtail's database of articles is searched and any matching articles are used to display a paragraph of text, highlighting the portion of the article which matches the query.
For more on Longtail Instant Answers, see the Longtail overview.
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