In general most projects would love to have some help. falkTX would like some help with his DISTRHO project. pgib would like collaborators on his lmms-lv2 project. Pretty much every dev I've talked to was excited to have someone offer to help. Unfortunately my productivity has fallen a lot so I didn't complete my tasks

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You can also submit patches and fixes to any project. Those are generally well received. If you are interested I dare say many projects would love help with documentation. Perhaps the best thing to do is to find a program/project you find very interesting or find something you'd like to fix. You'll likely be better motivated if you choose it rather than are assigned something. Thanks for offering to contribute to the community.