What is a .CLASS file?
CLASS is compiled Java bytecode, run by the Java Virtual Machine.
- Did you know
- Java bytecode dates from Java’s 1995 launch and runs unchanged on any device with a JVM.
- The format begins with the magic word “CAFEBABE”, a coffee-themed in-joke chosen by James Gosling’s team that foreshadowed the Java name.
- Analyser spots a .CLASS file by its signature bytes
CA FE BA BE- the playful hex word "CAFEBABE".
- What Analyser reads
- Identify and read metadata from developer and data files: JWT tokens (header + claims + expiry), WebAssembly, Java class files, NumPy/Safetensors/GGUF model files, source maps, SQL dumps, Visual Studio/.NET projects, Terraform, Protobuf, GraphQL, SARIF, Python bytecode, and Apple property lists (XML + binary). Jupyter notebooks (IPYNB) and HAR captures now open in a full viewer - see Notebooks & data above.
- Depth of analysis
- .CLASS is an identification-grade format: Analyser recognises it from its bytes and decodes the header metadata it carries, rather than opening it in a full viewer. Formats that do get a full viewer are marked "Full" on the formats page.
- Open a .CLASS file
- Drag a .CLASS file onto the Analyser home page (or tap to pick one). It is identified entirely in your browser - nothing is uploaded, there is no account, and it works offline once installed.