Examples of people offering their services on the EA Forum.
Important post to read before offering free services on the EA Forum: https://forum.effectivealtruism.org/posts/rPj6Fh4ZTEpRah3uf/problems-with-free-services-for-ea-projects
If you’d like to offer services specifically to the animal welfare community, follow this link: https://www.animaladvocacycareers.org/skilled-volunteering