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Aspell vs. LanguageTool (with test results)


I’m the maintainer and founder behind
I recently changed from Aspell to LanguageTool in order to provide not only spell but also grammar checking to our mostly German and English mobile users.

After the “relaunch” I received a couple of angry messages from long-time users like this:

I previously love this site, but honestly, the new interface is not
working like the old one. Word recommendations previously was
awesome, what I experienced today, very sad. […] The former site offered so many more word choices especially if I
phonetically spelled the words. What I experienced today was utter
disappointment to the previous word engine.

I sent this feedback to Daniel from the LanguageTool team. After he spent some time optimizing the suggestion generation we agreed on performing an A/B test by directly comparing Aspell vs. LanguageTool on SpellBoy. One test group received the full LanguageTool experience and the other the LanguageTool experience with suggestions provided by Aspell for misspellings.

In both cases I tracked how many users selected a suggestion and how many didn’t find the word they were looking for.

Results are quite interesting and I’m happy to share them with you:

As shown in the sheet LanguageTool performs slightly (0.35%) better for English and significantly (6.87%) better for German.

I’d like to say thank you to all LanguageTool contributors. It’s great to see how fast the project improves. Merry Christmas!

Kind regards from Germany,

1 Like

Great news! Thanks for sharing this.