- curl: Daniel Stenberg et al. - https://github.com/orgs/curl/people
- Lua (programming language): team of 3 - https://www.lua.org/authors.html
- openssl: 15 people - https://github.com/orgs/openssl/people
maybe also: sqlite, vim, nginx, redis
- Lua (programming language): team of 3 - https://www.lua.org/authors.html
- openssl: 15 people - https://github.com/orgs/openssl/people
maybe also: sqlite, vim, nginx, redis
SQLite won't accept contributions from outside the core team; joining the core team is an involved process, as they're taking extreme measures to ensure it will continue to be recognised as a work in public domain in as many jurisdictions as humanly possible. You can still support the project by paying them for their work (or by getting your employer to do so):
TL;DR: they have a company that legally employs every single co-author, to be able to sell you a Warranty of Title, just in case your company/jurisdiction/etc has a problem with public domain.
How many maintainers for the other ones you mentioned?
Redis team consists of 8 people: https://github.com/orgs/redis/people