Sundsvall (Swedish pronunciation: [ˈsɵn(d)sˈvalː]) is a city and the seat of Sundsvall Municipality in Västernorrland County, Sweden. It has a population of 50,712 as of 2010; more than 95,000 live in the surrounding municipal area.

The town was chartered in 1621, and a first urban plan for Sundsvall was probably created by Olof Bure in 1642, less likely in 1623. It has a port by the Gulf of Bothnia, and is located 395 km north of Stockholm. The city has burned down and been rebuilt four times. The first time, in 1721, it was set on fire by the Russian army during the Great Northern War. The last fire, in 1888, was the largest in Sweden's history. It is presumed that the fire was caused by a spark from a steamship. After that fire, the city centre was rebuilt only with stone buildings. Sundsvall's centre is therefore nicknamed Stenstaden (the stone city).

According to one historian,^[who?] Swedish industrialism started in Sundsvall when the Tunadal sawmill bought a steam-engine driven saw in 1849. In the early 20th century Sundsvall was an even greater centre of forestry industry in Sweden than it is today. The first large Swedish strike was the "Sundsvall strike" in 1879. The industrial heritage makes social democrat and socialist sympathies more prevalent in the Sundsvall region than in Sweden as a whole.