HSL may refer to:
- Companies
- Heeling Sports Limited, which owns the Heelys and Soap Shoes brands
- Hindustan Shipyard Limited in Visakhapatnam, India.
- Science, technology and computing
- HSL color space (hue, saturation, lightness)
- High Speed Link in telephony
- Homoserine lactone, a bacterial quorum sensing molecule
- Hormone-sensitive lipase, a protein found in the cytosol of adipocytes important in the hydrolysis of triacylglycerols.
- Harwell Subroutine Library, a library of FORTRAN Numerical Analysis Subroutines.
- Health and Safety Laboratory, an agency of the Health and Safety Executive in the UK.
- Transport
- Hogesnelheidslijn, high-speed railway lines iin the Netherlands: HSL-Zuid, HSL-Oost
- High Speed Line, high-speed railway lines in Belgium: HSL 1, HSL 2, HSL 3, HSL 4
- Haslemere railway station in Haslemere, Surrey, England
- Helsingin Seudun Liikenne, a public transport administration in Helsinki
- Other
- Hawaii State Library
- Helicopter Anti-Submarine Squadron (Light), in the United States Navy
- Hero of Socialist Labor, an honorary title and the highest degree of distinction for exceptional achievements in economy and culture in the Soviet Union.
- Hamburg School of Logistics, now Kühne School of Logistics and Management, a German business school
- Helsingin Shakkiliitto, a Finnish chess organization