Nagra is a generic term referring to any of the series of professional audio recorders produced by Kudelski S.A., based in Cheseaux-sur-Lausanne, Switzerland.

Nagra-brand tape recorders were the de-facto standard sound recording systems for motion picture and single-camera television production until the 1990s. Their physical appearance, with the single transport selector and large reel-to-reel tape deck are still the stereotypical image most people have of a professional tape recorder. A Nagra recorder prominently appears in the 1981 movie Diva, that features an opera fan making bootleg tapes of his favorite opera singer. The word "nagra" comes from Stefan Kudelski's mother tongue (Polish) and stands for "[it] will record".

The analogue Nagra recorders have a reputation for extreme ruggedness and reliability, essentially being the "Swiss watch" of audio tape recorders. Their cases are highly durable, and every component, from the transport rollers to the gain pots have the feel of bulletproof engineering. The feature that gave Nagra the edge in quality and film use was Stefan Kudelski's development of the Neo-Pilottone system, where synchronization data could be recorded on the tape in the middle of the audio track, but without crosstalk onto the program recording.

Nagra recorders are identified by their model number, which indicate their technological generation and features:

• Nagra III NP - The first Nagra usable for film work, first appearing in 1962
• Nagra IV-L - Monaural, featuring two microphone inputs and a built in audio limiter . Introduced in 1968.
• Nagra 4.2 - Same as the IV-L, but added powering for microphones and built-in equalizers. Introduced in 1972. In the '80s one could upgrade a 4.2 to record SMPTE timecode.
• Nagra IV-S - Stereo Nagra, recording two track stereo. It had dual level pots, limiters, and equalizer presets. It was introduced in 1971. Originally it was available with a pilottone crystal, and then in 1984, with timecode support. With timecode support a IV-S became a Nagra IV-STC

In addition to these field recorders, Kudelski S.A. produced a studio recorder called the Nagra T-Audio, designed mainly for use in telecines for transferring dailies. All analogue Nagras recorded on 1/4" tape.

The Nagra IV-STC was the standard until the mid-1990s, when DAT recorders became reliable enough to use in the field. In response, Kudelski produced two digital recorders to compete:

• Nagra D - 4-channel PCM digital audio recorder. Instead of recording to the DAT format, the D used a digital reel-to-reel format. This, combined with its heavy weight made it somewhat unpopular with many production sound mixers, but year after year many great-sounding films are completed with Nagra Ds (and the newer 24-bit/96 kHz Nagra DII), and its use is not immediately waning.
• Nagra V - 2-channel PCM digital audio recorder, 24-bit/96 kHz, removable hard drive based recorder with timecode support. Has the additional benefits of being very light, and producing files easily processed by non-linear editing systems.

Aside from its line of motion picture sound recorders, Kudelski S.A. originally produced and continues to produce high-quality recorders for electronic news gathering, radio, and music recording. The ARES-PII hand-held recorder for journalism and the Universal digital recorder the ARES-BB, both introduced in 2004 are state-of-the-art digital recorders recording to PCMCIA compact flash cards. They offer USB file download and can record both linear PCM or MPEG compressed audio.