DC-International is an analog audio cassette format developed by Grundig and marketed in 1965. DC is the abbreviation of "Double Cassette", as the cassette contained two reels; International was intended to indicate that, from the beginning, several companies around the world supported the format with suitable tape cassette recorders, recorded music cassettes and blank cassettes. Since DC-International did not compete effectively against the similar Compact Cassette, it was discontinued in 1967. In 1971, Grundig would later introduce a dictation cassette format known as Steno-Cassette. Unlike DC International, Steno-Cassette would become popular and widely used within Germany.

Starting in 1961, Philips (in conjunction with Grundig) began work in its Vienna tape production facilities, on a (HiFi)-compatible single-hole cassette. At the same time, a Philips team in Belgium developed a 2-hole cassette, under the name Pocket Recorder (later-named Compact Cassette). Philips' management finally gave preference to this development, but informed its partner Grundig rather late, which led Grundig - who received an offer to participate in the Pocket Recorder, to abandon the DC-International cassette it developed without further ado. This was based upon construction drawings of the compact cassette, which Grundig had taken after their negotiations with Philips.

The DC-International system was presented at the 1965 Stuttgart, Germany, radio exhibition. At that time, Grundig was the largest tape recorder manufacturer worldwide and wanted to be represented in the newly created tape cassette market, as well.

The DC-International cassette is a two-roll cassette tape which can be flipped over. The dimensions of a tape cassette (according to the DC-International system) are 120 mm × 77 mm × 12 mm, the weight is 65 grams (2.3 oz). The case is made of polystyrene, and a viewing window with scale incorporated into it, was included, so a user could view the tape from both sides of the cassette. The cassette has openings for the tape head and the erase head, as well as for the capstan pinch roller. A built-in pressure pad provides for tape-head contact.

Like the Compact Cassette would later have, a recording lock against unintentional erasure of a cassette was present in the form of 2 recesses in the cassette. If an opening is closed, it prevents any recording on that side. For protection against dust and scratches, the cassette can be inserted into a protective case when not in use. The tape's capable of recording 2 soundtracks in opposite directions. The tape speed is 5.08 cm/s = 2 ips, slightly faster than the Compact Cassette. Recording and playback in stereophonic sound would be possible with stereo devices, but there were never any such devices manufactured for this cassette format.

For a 90-minute DC-90 cassette (45 minutes per side), the tape length is 137 m with a triple play band (PES 18, thickness 0.018 mm). For a 120-minute DC-120 cartridge (60 minutes per side), the tape length is 185 m with quadruple play band (PES 12, thickness 0.012 mm). The tape itself consisted of polyester.

With the DC-International format, the focus was on music playback right from the start. At its launch, there were 25 pre-recorded music cassettes from Telefunken, Decca and RCA Victor available. These recordings on the cassettes ranged from country music to The Rolling Stones, the playing time is about 30 minutes per side. With a total playing time of about 60 minutes available, this was comparable to a phonograph record. The selling price of a pre-recorded cassette was 24 DM.

For home recordings, unrecorded, blank cassettes were available from Grundig, Telefunken, BASF and Agfa-Gevaert. These blank cassettes were available as both 90 minutes and 120 minutes of running time. A DC 90 blank cassette cost 12 DM, and a DC 120 blank cassette 15 DM.