SymSpell: Symmetric Delete Spelling Correction

What is SymSpell?

SymSpell is a correction algorithm similar to the Norvig model, except it is optimized for speed. It can perform spelling correction at up to 1 million times faster than the Norvig model. This allows us to utilize a larger dictionary and search a larger list of corrections (e.g., consider words with an edit distance of 3) without suffering from performance issues.

This is accomplished by simplifying our transformations. In our standard model, we utilize deletes, transposes, replaces, and inserts. SymSpell optimizes this by only using deletion operations and by creating a trie (prefix tree) as a precomputation measure.