Soccerway

* Exhaustive calendar of games by future date

* Worldwide league data covering 1,482 global leagues, 89 continental competitions and every national team

* Easy-to-read squad data

* Result info presented in helpful colour-coding

Soccerbase

* Player appearance data in handy list form, with brief statistics

* Performance data with/without certain players (up to two using ‘player filter’)

Wikipedia

* The best season-by-season breakdown around, often including position after each match, colour-coded W/D/L and appearance data

Whoscored

* Strength and weakness assessment of each team, which can guide more detailed scrutiny.

* Formation summary for each club. The ‘squad list’ option shows which players have played in which position and how often.

* Detailed team data in and intra-league comparison, broken down into shot zones, accuracy, body part, key passes, pass length, fouls, passes dribbles etc

* Detailed player data within teams and intra-league, again broken down into shot zones, accuracy, body part, key passes, pass length, fouls, passes dribbles etc

Fbref

* The most detailed player performance data available for free, including things you don’t get anywhere else.

11v11

* League table generator for any date (English leagues only)

* Club’s record against another team (with match data)

* Club appearance data season-by-season

Soccerstats

* Useful league stats (for lots of European leagues), with a few examples that you can’t find easily elsewhere: records when scoring and conceding first, goals per 10/15 minutes, time spent leading/trailing

* Handy club information of results against other clubs by league position:

Transfermarkt

* All transfers in a club’s history (occasionally beware the often slightly off values)

* Some unique insights: attacking partnerships, youngest/oldest players by season, youngest/oldest average XIs, players’ penalty records

* Creation of custom tables (choose your clubs and your seasons and create table)

* Managers’ records against other managers and clubs and their most-used players

Worldfootball.net

* Great historical database of worldwide squads and games

* View clubs by historical season squad list and results plus A-Z historical player list

* Great lineup information for old matches (although only goes back so far) using the historical results

Foot Stats

* The best referee database I’ve found (English leagues only)

OTHER WEBSITES

Bdfutbol - Reams of information (present and historical) on domestic leagues and clubs across Europe.

Rsssf - The bible of historic league tables and competition history worldwide. Functional design, exhaustive content