The Gründerzeit (German pronunciation: [ˈɡʁʏndɐˌtsaɪt] ^ⓘ; lit. 'founders' period') was a period of European economic history in mid- and late-19th century Germany and Austria-Hungary between industrialization and the great stock market crash of 1873. Its name is derived from the many incorporations of companies that occurred in the years between the Franco-Prussian War and the panic of 1873.

The term also refers to a cultural and architectural era which began in the mid-19th century and lasted until 1914. Gründerzeit architecture is closely associated with historicism, and occupies a prominent place in many Central European cities due to 19th-century urbanization.

The years constituting the economic Gründerzeit are not universally agreed-upon. In the most narrow sense, the term refers to the two years following the founding of the German Empire in 1871 (also called the Gründerjahre, or "founder's years"), in which French war reparations from the Franco-Prussian War charged massive growth and speculation. Some economists have postulated that the era began in 1869, a year in which corporate law and the Handelsgesetzbuch were liberalized across Germany. Others put the beginning of the period in the 1860s, or earlier, while most agree on the 1873 end-date. Alternatively, German historian Christian Jansen delineates the period as lasting from the Revolutions of 1848 to the founding of the German Empire. Nikolai Kondratiev described the economic upswing in which the Gründerzeit occurred as the growth phase of the second Kondratiev cycle.

Industrialization and urbanization opened new stylistic frontiers, especially in architecture. However, industrialization's rapid and drastic changes also engendered a reaction, with many artists and members of the bourgeoisie turning to history and tradition (see romanticism). This resulted in an eclectic development of existing forms. "Gründerzeit style" is a term often inseparable from historicism. Because historicism remained a predominant style until after 1900, the delineation of this art-historical era is imprecise. In the context of stylistic history, it can refer to varying periods within the nineteenth and early twentieth centuries, such as 1850–1873, 1871–1890, and sometimes even 1850–1914. The distinction of the Gründerzeit from other periods (such as the Belle Époque) is not delineated.

According to conservative definitions, the Gründerzeit was a very short-lived, but extraordinarily productive economic boom at the beginning of the German Empire. Hundreds of new businesses, banks and railways were founded in the few years assigned to the period. The founding of joint-stock companies was crucial to the growth of the German economy: in Prussia, between 1867 and 1860, 88 of them were founded; between 1870 and 1873, 928 were founded. However, as discussed prior, its beginning date has been placed as far earlier; any periodization includes Germany and Austria-Hungary's rapid economic development.

A decisive factor in this rapid economic development was the construction of new railways. Typical “founders” were therefore railway entrepreneurs such as Bethel Henry Strousberg. Railroads had a significant stimulating effect on other branches of industry, for example through the increased demand for coal and steel, so that industrial empires such as that of Friedrich Krupp emerged during the Gründerzeit. Mass production of non-industrial goods, such as foodstuffs, was made possible during this period by the birth of railroads. Perhaps most importantly, communication and migration were made much easier. Rural lower classes migrated en masse to the cities, where they became part of the emerging proletariat: in Germany, the expanded Gründerzeit was the time in which the social question was first addressed by socialists.

Reparations payments from the French Third Republic were enormously stimulating to the German economy. The five billion gold Francs which the French state agreed to send were melted down and recast as gold Marks. Simultaneously, the new German state sold off its silver reserves and bought more gold on the world market. To counteract a devaluation of the silver currencies caused by the high amount of silver on the market, France was forced to limit the minting of silver coins (see Latin Monetary Union).

German writers of the late 19th century used the term Gründerzeit as a pejorative, because the cultural output of that movement was associated with materialism and nationalistic triumphalism. Cultural historian Egon Friedell complained that fraud in the stock market had not been the only swindle of the Gründerzeit, lambasting greater cultural trends of the time.