These are some of my favorite OSINT sites. I use them consistently in my research
MIchael Bazzell’s site is consistently updated when API changes happen that break the look up tools. Bazzell does a great job of keeping his radar on the best new OSINT tools that come out. There is some great paid training options and books for sale on the site, but all of these lookup tools are free.
Justin Nordine @jnordine maintains the following site. Justin gets feedback direct from the OSINT community and makes changes based on researcher suggestions and audit of the resources. If you have a data point to pivot on go to that category and you will find a useful site or research tool to dig further.