A stamp vending machine (SVM) is a mechanical, electrical or electro-mechanical device which can be used to automatically vend postage stamps to users in exchange for a pre-determined amount of money, normally in coin. Most SVMs were positioned in public places to provide a useful service to customers when other sources of postage stamps, such as Post Offices were closed. The term is often applied to the entire object as found attached to a pillar box or sited in a wall. The name Stamp Vending Machine only applies to the internal mechanism, the housing is described by the UK Post Office as a "case" and was supplied, installed and maintained separately. Many postal administrations around the world have used automatic stamp vending machines including the United States, where private manufacturers began vending stamps from coils in 1908. Most countries of the Commonwealth of Nations have issued stamps for use in Stamp Vending Machines, including Hong Kong, New Zealand and Malta.

Many countries still use stamp vending machines; for instance, in Europe, France and Germany do. Their design, fairly modern, is similar to the kind of electronic interface you may find on a machine selling train tickets, or an ATM: a screen displays several buying options, possibly in different languages. A set of buttons on both sides of the screen allows to select the desired option. The process can involve several steps (i.e. first choosing the value of the desired stamps, then their number). These machines normally accept coins, and in France also debit cards. The French machine, located in post offices, can let the user weight the envelope so that the exact correct fare may be selected (depending on the destination country). The German machines, located either inside or outside post offices, don't feature a scale, but the user can type the value they want to see printed on the stamp, before selecting how many they want. The German machine doesn't give change in coins, but issues extra stamps with the remaining value. The French machines, however, do give exact change. In Australia, modern stamp vending machines are regular vending machines (the same types as snack machines) which issue bulk stamp packs (which are standard issue stamps rather than separate vending machine issues) as well as bulk parcel satchels; individual stamps or parcels are not available and only credit cards are accepted for payment due to the high costs of these items.