The best alternative to Gboard is FlorisBoard, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 50 alternatives to Gboard and eight of them are so hopefully you can find a suitable replacement. Other interesting alternatives to Gboard are OpenBoard, Simple Keyboard, Hacker's Keyboard and Keyboard Designer.
FlorisBoard is an open-source keyboard aimed at providing you with an easy way to type while respecting your privacy.
It is easy to use customize
It's ok, but the swipe typing isn't great. It doesn't show alternative word suggestions, so you can't quickly correct, you gotta go back and delete. If you don't use swipe then it's a solid alternative.
OpenBoard is a 100% foss keyboard based on AOSP, with no dependency on Google binaries, that respects your privacy.
Last commit was in December 2022, and it's not available in the Google Play Store anymore. 
HeliBoard is an active fork
It's basically the open source alternative to Gboard doing all the same while also being privacy-oriented and trustworty (unlike proprietary virtual keyboards that undoubtedly are not your friend, unfortunately). OpenBoard is a no-brainer and I urge people to try it. :)
There is a numpad layout but no option to default to it. The defaults (like auto-correction enabled) could be better. But it's still my preferred keyboard, especially as the fork fixes some annoyances: https://github.com/Helium314/openboard
It looks similar to Gboard, so doesn't take much time getting used to it. It also looks very clean and polished
Small open-source keyboard with minimal permissions offers adjustable height, number row, navigation keys, customizable themes, and no ads, emojis, spell check, or swipe. Ideal for those preferring basic functionality without extra features or background data use.
Awesome 808 KB size keyboard. Very helpful in old mobiles.
I'd definitely have this over Gboard, but I'd have OpenBoard over Simple Keyboard.
Are you missing the key layout you're used to from your computer when using an Android device? This software keyboard has separate number keys, punctuation in the usual places, and arrow keys. It is based on the AOSP Gingerbread soft keyboard, so it supports multitouch for...
The last update is from April 2021.
Keyboard shortcuts like with a full size keyboard!
the best to write commands in terminal
Customizable Android keyboard with user-defined layouts, per-key settings for tap, hold, swipe in all modes, supports downloadable and user-imported word lists, no permissions needed, works fully offline, includes Wear OS support, expandable features via optional packages.
We want to create the fastest, the most accurate and the most comfortable touchscreen keyboard in the World.
Thumb Keyboard for Android is a keyboard with many, advanced customization options that allows the user to adjust it to his or her preferences. This groundbreaking keyboard introduces a lot of innovations.
Omera is an AI writing keyboard that helps you write with confidence using grammar correction, tone adjustment, translation, and smart writing suggestions across any app.
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It would take Openboard's place if dev didn't sleep on this project, as it doesn't have basic dictionary and auto correct