Here are some useful EVE Online third party tools and websites, as well as other handy information. Please send our CEO an in-game mail if you think something should be added!
Guristas - Kinetic/Thermal
Serpentis - Thermal/Kinetic
Blood Raider - EM/Thermal
Sansha's Nation - EM/Thermal
Angel Cartel - Explosive/Kinetic/EM/Thermal
Mordus - Kinetic/Thermal
Rogue Drones - Explosive/Kinetic/Thermal/EM
Sleepers - Kinetic/EM/Thermal/Explosive
Triglavian - Thermal/Explosive
The EVE University Wiki is a treasure trove of useful information about all things EVE Online. Personally we use it quite often as a guide when doing various PVE sites. You can either visit the site, or you can for example search for the name of a PVE combat site and it will often direct you to an EVE University wiki page.
Website: https://wiki.eveuniversity.org
EvE-Scout or the Signal Cartel has a website with regularly updated wormhole connections to the Thera wormhole as well as the Turnur system. You can connect to the shared bookmarks folder through their public channel EvE-Scout. They also run a wormhole rescue service, which I have linked below.
Website: https://www.eve-scout.com
Rescue Service: https://evescoutrescue.com/home
Python Fitting Assistant, or Pyfa as it's called is a software program available for Windows, Linux and Mac computers that can be used to create ship and citadel fittings. You can import the skills of your characters into the program and see the stats of your ship fittings without even logging into the game. It's also possible to export the ship fittings to your clipboard and then import them into the game.
Website: https://github.com/pyfa-org/Pyfa/releases
Zkillboard is perhaps the most important intelligence gathering tool in EVE Online. On Zkillboard you can see all the publicly available killmails in the game. In the killmails you see what fittings the destroyed ship had, what modules dropped, who killed the ship and what ships they were flying. It's simply an invaluable tool.
Website: https://zkillboard.com
With Localthreat you can copy and paste the people in local chat and get an instant intelligence report on whether or not they are a threat. Localthreat accesses their Zkillboard history and displays how dangerous the pilots are and what ships they have recently used in killmails.
Website: https://localthreat.xyz
Dotlan EVE Maps is a website that has a map of the entire New Eden universe, with the exception of wormhole space. Here you can look up any system on the map and see important data about them. Like how many ships and pods have been killed recently, how many NPC kills there have been in the past hour or 24 hours, how many jumps there have been, who owns a system which can be useful in nullsec. You can even find out what systems are reachable via jump drive of a jump freighter, capital ship or black ops battleship. It's a treasure trove of information.
Website: https://evemaps.dotlan.net
EVE Gatecheck allows you to input a travel route and find out if there has been any killboard activity in the past hour on your route. This is useful if you are traveling through potentially dangerous systems.
Website: https://eve-gatecheck.space/eve
Anoik.is is a useful tool for those who like to travel in wormhole space. You can go to the website, enter the J-code of a wormhole system you're in, and get valuable intel on the wormhole system. For example it will tell you the wormhole class, what static wormholes it has, when the last killboard activity was, what corporations may live in the wormhole and more.
Website: http://anoik.is
If you want to find out the value of some items in different systems and not travel there manually, one useful tool is the EVE Tycoon Market Browser. You can simply type the name of the item and search for it, then EVE Tycoon will show you the buy and sell orders for that item in many different systems around New Eden. The prices are not real time but they are frequently updated.
Website: https://evetycoon.com/market
With Janice you can copy and paste a list of various items and check the value of those items in a few different trade hubs in the game, like Jita, Perimeter and Amarr. If you are exploring and doing hacking sites, you can cargo scan the containers, copy the contents into your clipboard, paste the list of items into Janice and check the price. If it's just cheap items, then you can skip the can and move on to others with more valuable items. You can also paste ship fittings and see how much they are valued in the major trade hubs.
Website: https://janice.e-351.com