The Helsinki Regional Transport Authority (Finnish: Helsingin seudun liikenne, HSL; Swedish: Helsingforsregionens trafik, HRT) is the inter-municipal authority that maintains the public transportation network of the nine municipalities of Greater Helsinki, Finland.

HSL was founded on 1 January 2010[3] on the basis of the Finnish public transportation law, joukkoliikennelaki, which was adopted on 3 December 2009.

In 2016, HSL started to develop a new version of its native journey planner, Reittiopas, originally released by YTV in 2001.

The replacement intermodal public transport route planner, called Digitransit, is built on the open source OpenTripPlanner.

[5] The official name of the transport authority is Helsingin seudun liikenne -kuntayhtymä HSL in Finnish and Samkommunen Helsingforsregionens trafik HRT in Swedish.

However, apart from select bus routes with electric units, the agency does not operate any rolling stock.

The first phase of the Länsimetro expansion program extended the metro lines west to Lauttasaari and southern Espoo, serving eight new stations.

The system is sponsored by HOK-Elanto's grocery shop chain Alepa, which has purchased the commercial space on the bicycles.

In late 2016 HSL announced the details of a revamped bikeshare system, this time spanning 1,500 bikes and 150 stations.

Apart from the bus network, all of HSL's services use a proof-of-payment system: there are no gates at metro and commuter rail stations or tram stops.

Instead, passengers are required to present a valid ticket to fare inspectors, who randomly patrol the network.

[9] HSL is owned by the cities of Helsinki, Espoo, Vantaa, Kerava, and Kauniainen and the municipalities of Kirkkonummi and Sipoo.

The other municipalities in the Greater Helsinki area (Järvenpää, Nurmijärvi, Mäntsälä, Pornainen, Hyvinkää, and Vihti) have the possibility of joining HSL in the future.

After the founding of HSL, the visual identity of all transportation services in Helsinki was unified under one brand name and logo.

HSL began installing new fare card readers on public transportation vehicles in 2016.

HSL's customer and sales manager, Mari Flink, said that the company was conducting user tests regarding the ease of use of fare card readers.

[18] HSL's first CEO, Suvi Rihtniemi, retired and on November 3, 2020, Mika Nykänen was selected as her successor.

Nykänen will come from the position of director of the Geological Survey of Finland and has no previous experience in public transportation.

The Helsinki Administrative Court overturned HSL's decision, stating that students are entitled to receive discounts on physical fare cards in addition to the app.