Hattrick was launched in 1997. At that time, Björn Holmér was the sole developer of the game. Its initial launch lasted only seven weeks (or rounds), and all changes to the team were made by submitting a HTML form with the user's username and password, meaning that the user never actually logged in to the interface. The release was re-coded and Version 2.0 was launched. The new release allowed for a total of 680 teams and added a few features still available today, such as the transfer list and a league pyramid (though teams' positions in the series were determined by random selection during the offseason). Season two also saw the first ever international match, between Sverige and Danmark, with Danmark winning 1-2. This match was relatively meaningless, however, since the teams' players were clones of each other. A new version was re-launched the following season, and this release marked the debut of friendly matches and cup matches. The following season, Season 4, also added features such as training types beyond General, Set Pieces, and Stamina, and an expanded set of in-game skill levels.
Season 7, which began in July 1999, marked some real progress in the game. New tactical options were added so that teams could change their formation from the fundamental 4-4-2. Teams could also set their players' individual tactics, such as offensive or defensive. After Season 7, ExtraLives AB was formed and the team began development of Version 5.0. Roughly nine months later, Hattrick V.5 was launched.
Season 11 marked the launch of Hattrick 5.0, and with it the current graphical interface. Hattrick also added more nations beyond Sverige: Danmark, Suomi, Argentina, Deutschland, England, Italia, México (originally as Spain), and USA. Users who had previously played in Sverige and new users alike filled these nations. At this time the game had a capacity of roughly 12,000 users. The launch of Hattrick 5.0 shaped the game as it is today, adding features such as live matches, which replaced the matches that previously occurred during downtime each night, instant transfer processing, 15 different player skill levels including the current peak level 'divine,' and the "stars" system for player performance rating.
- New leagues: Argentina, Danmark, Deutschland, England, Italia, México (originally as Spain), Suomi, USA.
At the beginning of Season 12 teams were placed in the same series as they finished and the promotion/demotion system was established. Hattrick Supporter was launched before Season 13.
- new leagues: Brasil, Canada, Chile, China, Colombia, España, Hanguk, India, Ireland, Misr, Nippon, Oceania, Perú, Polska, Portugal, România, Rossiya, Scotland, South Africa, Türkiye, Uruguay, Venezuela.
Conferences system and Hattrick mobile were added for Season 14.
Season 15, which began in January 2002, marked the launch of Version 6, the current version of Hattrick. Version 6 added the first official national teams, and with it World Cups and international friendly matches. The first World Cup was held at the end of the season, with Sverige beating England 4-0. The developers also added special events, a concept very familiar to those playing today. Special Events allowed players with special traits (such as Powerful or Head specialist) to perform a certain way in a match, whether by scoring a goal, surprising an opponent, or growing more tired due to the sun. Version 6 did not solve the growing economic problems within the game, however. The developers resorted to giving out 200,000 Euros (or the equivalent in each country's currency) to each team to boost the in-game economy, which had entered the equivalent of a depression.
- new leagues: Česká republika, Eesti, Hellas, Hrvatska, Indonesia, Latvija, Magyarország, Philippines and Srbija i Crna Gora;
- The first U-20 World Cup is played.
- new leagues: Bulgaria, Cymru, Israel, Slovenija (because of an error their first season is called 'season 2');
- VI. Division established in España, Nederland and Deutschland.
- Hattrick 6.5 was introduced;
- VI. Division established in Italia, Polska and Suomi;
- VII. Division in Schweiz.
- new leagues: Al Maghrib, Bolivia, Ecuador, Føroyar, Nigeria and Paraguay;
- IV. Division in Lietuva, Srbija i Crna Gora;
- V. Divison in Colombia, Hellas, Ireland, Uruguay;
- VI. Division in Chile, France, Israel, Österreich;
- VII. Division in Argentina, België, Deutschland and España.
- new leagues: Saudi Arabia, Tounes, Costa Rica, Lëtzebuerg, Iran, Republica Dominicana, Cyprus and United Arab Emirates.
- new leagues: Northern Ireland, Belarus, FYR Macedonia, Panamá, Kenya and Jamaica;
- VIII. Division in Deutschland.
- new leagues: El Salvador, Honduras, Kyrgyzstan, Malta, Moldova and Shqiperia;
- IX. Division in Deutschland.
- new leagues: Al Jazair, Hayastan, Lubnan, Liechtenstein, Mongol Uls and Sénégal;
- VII. Division in England;
- XI. Division in Deutschland.
Announced more than a season in advance, the league reform was a major project that was completed during the off-season prior to season 29, in April 2006. At this time, the game's membership was 800,000 strong and the largest countries had swelled to over 60,000 users each, or 12 levels. The league reform intended to solve the problem of league pyramid capacity, since the growth of larger leagues, such as Nederland or Sverige, had made it necessary to add a new pyramid level almost every season. Before the league reform, the league pyramid only expanded in size from division 1 to division 6; pyramid levels in division 6 and below were all comprised of 1024 teams. Combined with the fact that new teams are only assigned in the bottom two divisions, this pyramid structure caused major problems with bot teams as they were accumulating in the lower divisions of large HT nations; Hattrick relies on the regular promotion/relegation system to move bot teams to the bottom of league pyramids over time.
When the bot problem was at its worst, about half of the teams in a league level in Argentina, a country that would otherwise fill its league pyramid, were bots, which barely offered any resistance for the active teams. To alleviate this problem, the league structure was changed so that levels 8 and 9 would double in size to 2048 leagues, and 10 and below would increase to 4096 teams. Following this restructuring, all bot teams at that time were relegated to the bottom division, replacing them by promoting extra teams from lower divisions.
- new leagues: Al Kuwayt, Angola, Bangladesh; Srbija i Crna Gora will be divided into two separate leagues: Srbija and Crna Gora.