What is the RSC file format?
An .rsc file is a compiled binary resource file used by Symbian OS, the mobile operating system powering Nokia Series 60, Series 80, and UIQ handsets through the 2000s and early 2010s. Resource files store UI strings, dialog layouts, menu structures, and other non-executable assets that a Symbian application needs at runtime.
.rsc files are produced by compiling .rss (Resource Script Source) text files using rcomp, the resource compiler shipped with the Nokia Carbide.c++ SDK. The compiled output is packaged inside a .sis or .sisx application installer and deployed to the device's resource directory. At runtime, the Symbian application framework loads the .rsc to render the UI without embedding strings directly in the executable.
The binary structure begins with a 12-byte Symbian UID triplet (UID1, UID2, UID3) followed by a 4-byte CRC32 checksum - the standard Symbian compound-document header. An index table maps resource IDs to byte offsets within the file, followed by the resource data entries. The format evolved from EPOC Release 5 (Psion PDAs, circa 1997) through Symbian OS v9; v9 changed section alignment rules.
Symbian OS reached commercial end-of-life in 2013. The .rsc extension is also used, entirely unrelated, by Pegasus Mail, MicroStation (CAD), and Maptitude (GIS) - each with a completely different binary structure.
Security & safety
RISK: LOWSymbian RSC files are compiled data files with no execution capability on Windows/macOS/Linux. They are inert outside a Symbian device/emulator context.
Format details
in a nutshell- Pegasus Mail Resource File - Used by Pegasus Mail email client to store UI resources; unrelated binary format.
- MicroStation Resource File - CAD resource data for Bentley MicroStation; proprietary binary, different structure.
- Maptitude Resource File - Geographic/mapping data file used by Caliper Maptitude GIS software.
Programs that open RSC files
Windows3 apps
Nokia Carbide.c++ (legacy)
Free Open the RSS source and compile/decompile RSC via Symbian SDK tools (rcomp). Note: Carbide.c++ is no longer distributed officially - use archived copies.
Nokia Symbian rcomp (SDK tool)
Free Command-line compiler/decompiler in the Symbian SDK: rcomp -u resource.rsc decompiles to human-readable RSS. Technical details
deep spec| File encoding | Binary |
| Byte order | Little-endian (ARM architecture) |
| Header | 12-byte Symbian UID triplet (UID1/UID2/UID3) + 4-byte CRC32 checksum |
| Internal structure | Resource index table (resource ID to byte-offset mapping) followed by packed resource data entries |
| Storage format | Resource entries stored as uncompressed binary; rcomp outputs raw compiled data with no compression step |
| Source format | Compiled from .rss Resource Script Source text files using the rcomp compiler |
| Build tool | Nokia Carbide.c++ SDK (Eclipse-based); rcomp resource compiler included in SDK |
| Typical size | 1 KB - 500 KB |
| Deployment | Packaged inside .sis/.sisx installer; extracted to device \Resource\Apps\ directory at install time |
| Paired files | Accompanies an .APP Symbian executable and optional .MBM (Multi-Bitmap) file |
| Format evolution | EPOC Release 5 (1997) through Symbian OS v6-v9; v9+ introduced different section alignment |
| Extension conflicts | .rsc also used by Pegasus Mail, MicroStation (CAD), and Maptitude (GIS) - all unrelated binary formats |
| Platform status | Symbian OS EOL 2013; Nokia transferred platform to Accenture; SDK no longer officially available |
| Released | circa 1997 (Symbian OS / EPOC platform) |
| Latest version | N/A (tied to Symbian OS SDK; Symbian OS EOL 2013) |
RSC conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about RSC files.
