| Official Name: | Österbybruk |
| Pushpin Map: | Sweden Uppsala#Sweden |
| Subdivision Type: | Country |
| Subdivision Name: | Sweden |
| Subdivision Type3: | Municipality |
| Subdivision Name3: | Östhammar Municipality |
| Subdivision Type2: | County |
| Subdivision Name2: | Uppsala County |
| Subdivision Type1: | Province |
| Subdivision Name1: | Uppland |
| Area Footnotes: | [1] |
| Area Total Km2: | 2.51 |
| Population As Of: | 31 December 2020 |
| Population Footnotes: | [2] |
| Population Total: | 2,375 |
| Population Density Km2: | auto |
| Timezone: | CET |
| Utc Offset: | +1 |
| Timezone Dst: | CEST |
| Utc Offset Dst: | +2 |
| Coordinates: | 60.2°N 71°W |
Österbybruk is a locality situated in Östhammar Municipality, Uppsala County, Sweden with 2,272 inhabitants in 2010.
The Österby works was one of a number mostly in Roslagen, where there were Walloon forges, producing high quality oregrounds iron for export. Österby's brand mark was OO. All iron was branded with that mark. The Österby ironproducts were highly valued in England for the production of blister steel by the cementation process.
The historical complex of Österbybruk is a "Vallonbruk", a social and economic building complex surrounding a forge. Österbybruk is one of the most beautiful examples of the remains of the presence and input of Walloon immigrants ('valloner') in Sweden in the 17th century. More than 1.200 families emigrated in that era to Sweden, where the expertise of Walloon master blacksmiths was highly sought after. They helped to launch the Swedish iron and metal industry. The number of their descendants is estimated today between 500.000 and 1 million people.[3]
Österbybruk has a humid continental climate that is quite mild throughout the year, especially considering its northerly latitude.