| Extension | File Type | Files scanned | Contributor |
| R2A | Yamaha RS7000 - All data | 2 | |
| R2P | Yamaha RS7000 - Pattern data | 2 | |
| R2S | Yamaha RS7000 - Song data | 2 | |
| R3A/R3P | Yamaha RS7000 - Sample data | 3 | |
| R8 | Cubicomp PictureMaker red channel image data | 15 | |
| RA | RealAudio sound | 3 | |
| RAD | Reality ADlib tracker module/song | 7 | |
| RAF | Fuji raw image | 9 | |
| RAM | RealMedia meta file | 4 | |
| RAR | RAR Archive | 35 | |
| RAR | WinRAR interface theme | 9 | |
| RAS | Max Payne data file | 8 | |
| RAS | Sun Raster bitmap | 6 | |
| RATDVD | ratDVD DVD image | 4 | |
| RAW | Image Alchemy HSI temporary raw bitmap | 15 | |
| RB | Rocket eBook | 35 | |
| RB4 | Resume Builder 4.x | 3 | |
| RBC | Easy Resume Creator Pro resume | 5 | |
| RBJ | Redcode Object XRA PC (v1.x) | 243 | |
| RBS | Propellerhead Software ReBirth Song | 9 | |
| RBT | LEGO NXT brick | 24 | |
| RBT | REALbasic Project | 125 | |
| RCAD | RealCADD drawing | 12 | |
| RCL | Easy CD Creator Layout | 4 | |
| RCL | Recolored project | 4 | |
| RCS | RadDeveloper color scheme | 5 | |
| RD | Reaction Data file | 2 | |
| RDATA | R saved work space | 6 | |
| RDF | Friend of a Friend (FOAF) Resource Description Framework | 13 | |
| RDF | Resource Description Framework | 26 | |
| RDF | Yaesu radio memory file | 5 | |
| RDP | Remote Desktop Connection Settings | 4 | ptweasel |
| RDS | Ray Dream Studio | 20 | |
| RDW | Real-DRAW Project | 20 | Flarn2006 |
| REF | Atari ST Guide ref links | 4 | |
| REF | Lavasoft Ad-Aware reference file | 6 | |
| REG | Windows Registry Data | 11 | |
| REG | Windows Registry Data (Ver. 4.0) | 7 | |
| REG | Windows Registry Data (Ver. 5.0 - UTF16) | 4 | |
| REG | Windows Registry Data (Ver. 5.0) | 3 | |
| REKO | REKO cardset | 4 | |
| REP | Business Objects Report | 43 | |
| REP | Grand Theft Auto: San Andreas replay | 2 | |
| REP | Lotus Organizer Report | 36 | |
| RES | SNNS result | 8 | |
| RES | Windows compiled resource | 21 | |
| RESX | Microsoft .NET XML Resource template | 25 | |
| REV | Revolution MetaCard stack | 7 | |
| REX | ReCycled Audio Loop Export | 5 | |
| REZ | LinTech resource file | 5 | |
| RFL | Propellerhead Software Reason SoundBank | 8 | |
| RFN/RFP/RFX | RoboForm saved data | 8 | |
| RFO | RoboForm cached data | 3 | |
| RGB | Silicon Graphics RGB bitmap | 16 | |
| RGE | R.A.G.E. Driver | 25 | |
| RGO | RepliGo virtual print | 5 | |
| RGP | RealArcade Game Package | 7 | |
| RGS | InstallShield Script for Windows Registry | 15 | |
| RGS | RealArcade Game Installer | 2 | |
| RIB | Renderman RIB | 7 | |
| RIF | Rockwell ADPCM audio | 43 | |
| RIX/SCX | ColoRIX bitmap | 21 | |
| RJP | Vectordean Music | 31 | |
| RJS | RealSystem Skin | 4 | |
| RK | WinRK File Archive | 21 | Meigel |
| RKA | RKAU lossless compressed Audio | 11 | |
| RKP | REKO PC cardset | 3 | |
| RKP | RKP game package (v1.x) | 5 | |
| RKP | RemoteKeys profile | 18 | |
| RLA | Alias Wavefront Raster bitmap | 21 | |
| RLC | Radiant LoopCAD Project | 6 | |
| RLE | Run Lenght Encoded bitmap | 15 | |
| RLE | Utah Raster Toolkit bitmap | 21 | |
| RLG | RegCleaner v4.3 Language File | 40 | .Cryorb |
| RM | Real Media stream | 17 | |
| RM/RA | Real Audio | 14 | |
| RMF | Rich Map Format | 18 | |
| RMI | RMI RIFF MIDI Music | 5 | |
| RML | Redline Markup Language | 3 | |
| RMP | Real Metadata Package | 4 | |
| RMVB | RealVideo Variable Bit Rate | 7 | |
| RMX | RealMedia Secure clip | 7 | |
| RNG | RELAX NG | 14 | |
| RNS | Propellerheads Reason Song file | 2 | |
| ROC | SpaceCAD rocket model | 7 | |
| ROL | AdLib Visual Composer music | 105 | |
| ROM | MSX ROM Image | 22 | |
| ROM | MSX2 ROM Image | 12 | |
| ROQ | Id Software RoQ video | 4 | |
| ROT | Home World 2 - ROT graphics | 12 | |
| RP2 | RetroPlatform Player archive | 3 | |
| RPC | RAR Password Cracker project | 2 | |
| RPL | ARMovie video | 6 | |
| RPM | RPM Package (generic) | 25 | |
| RPS | Propellerhead Software Reason Song | 6 | |
| RPT | Crystal Reports output file (Report) | 19 | |
| RRD | Round-Robin Database | 9 | |
| RSG | Drakan: Order Of The Flame Saved Game | 82 | .Cryorb |
| RSH | Warhammer 40K textures | 4 | |
| RSM | Resume | 11 | |
| RSS | Rockwell Logix 500 SLC-5 Software | 22 | |
| RSY | FLEXIT Multishot Survey Raw Data file | 4 | |
| RTAB | RandyTab guitar tablature | 7 | |
| RTD | RagTime document | 9 | |
| RTE | Fugawi route format | 8 | |
| RTE | RTE encoded file | 2 | |
| RTF | Rich Text Format | 66 | |
| RTL | HP Raster Transfer Language | 30 | |
| RTM | Real Tracker module/song | 2 | |
| RUN | Rune map | 21 | |
| RUS | Navitel 1.1 Map | 5 | |
| RVL | Muvee project | 6 | |
| RWSD | RWSD Audio Stream | 2 | |
| RXE | LEGO Mindstorms NXT Executable | 2 | |
| RXF | Recipe Exchange Format | 13 | |
| RXF | Resco encrypted file | 9 | |
| RXN | MDL Reaction format | 5 | |
| RZ | rzip compressed archive | 2 | |
| RZX | File Crypt encrypted | 104 | Red Zion |
| RZX | RamSoft's ZX Spectrum Replay | 2 | |
