Extract text from Runescape cache files (IDX255)
To convert IDX255 cache files to another format, you need RuneScape Client or other Game software.
To convert other file formats to the "Cache Index File" file type, you need software like RuneScape Client or a similar tool.
The .idx255 file is a proprietary master cache index used by the RuneScape game client, developed by Jagex. It functions as the master reference table, instructing the game engine on how to read, verify, and extract compressed data from the main cache archive (typically a .dat2 file). Players, data miners, and developers interacting with private servers often encounter these files when attempting to unpack game assets.
Opening an .idx255 file is generally impossible with standard software. Because it is a compiled binary file containing only block pointers, version lengths, and metadata, it holds no inherently readable text or media. Users typically want to convert these cache files to extract 3D character models (OBJ), item textures (PNG), or game audio (OGG). However, the .idx255 file itself cannot be converted into these formats because it lacks the actual asset payload. To successfully extract assets, users must use specialized, community-built cache extraction tools like RuneLite dumpers or Tom's Cache Suite alongside the main data files.
This file format is exceptionally difficult to open or convert because it is closed, undocumented by the developers, and completely dependent on the presence of the main data archive. Standard online converters fail to process it because they expect standalone media, not a relational database index.
Convert.Guru analyzes your IDX255 file, detects the exact format, and lets you read the text inside.
If you want to convert IDX255 file to , you can use RuneScape Client or similar software from the "Game Cache Master Index" category. In the File menu, look for Save As… or Export….
To convert files to IDX255, try RuneScape Client or another comparable tool in the "Game Cache Master Index" category.
The history of Convert.Guru began over 25 years ago in California with Tom Simondi’s file-format database. A former contributor to Space Shuttle development and a software pioneer of the 1980s, Simondi established a trusted resource for file type analysis that was even referenced by Microsoft Windows XP. Today, we use modern technology to process and convert thousands of file formats while continually improving our IDX255 converter.