Dotsider 0.4.2

Dotsider

A TUI for analyzing .NET assemblies — structure, metadata, IL, strings, dependencies, and more. Inspired by binsider for ELF binaries, built for the .NET ecosystem.

dotsider HelloWorld.dll

Installation

dotnet tool (recommended)

dotnet tool install -g dotsider

Homebrew (macOS / Linux)

brew install willibrandon/tap/dotsider

WinGet (Windows)

winget install willibrandon.dotsider

Scoop (Windows)

scoop bucket add dotsider https://github.com/willibrandon/scoop-bucket
scoop install dotsider

Download binary

Grab a standalone binary from Releases.

What it does

dotsider opens any .NET DLL or EXE and lets you explore it across 8 tabs:

Additional modes

dotsider diff v1.dll v2.dll     # side-by-side assembly comparison
dotsider package.nupkg          # browse NuGet package contents, inspect any DLL inside

Building

Requires .NET 10 SDK.

dotnet build

The binary lands at src/Dotsider/bin/Debug/net10.0/dotsider.

Usage

dotsider <assembly.dll|.exe>    # TUI mode — interactive assembly explorer
dotsider <package.nupkg>        # TUI mode — browse NuGet package contents
dotsider diff <left> <right>    # TUI mode — side-by-side assembly comparison

dotsider analyze <file> [opts]  # CLI mode — headless analysis to stdout or file
dotsider sessions <command>     # CLI mode — interact with running dotsider instances
dotsider agent init [opts]      # CLI mode — generate AI skill file for a provider
dotsider agent mcp              # CLI mode — launch the dotsider MCP server

TUI options:
  -t, --tab <1-8>               start on a specific tab
  -n, --min-len <n>             minimum raw string length (default: 4)
  -v, --version                 show version
  -h, --help                    show help

CLI: dotsider analyze

Run analysis without the TUI — pipe to other tools, write to files, or output JSON for scripting.

dotsider analyze MyLib.dll                  # assembly info (default)
dotsider analyze MyLib.dll --types          # list type definitions
dotsider analyze MyLib.dll --methods        # list method definitions
dotsider analyze MyLib.dll --il Type.Method # disassemble a method
dotsider analyze MyLib.dll --deps           # assembly references
dotsider analyze MyLib.dll --strings        # extract strings
dotsider analyze MyLib.dll --size           # size breakdown
dotsider analyze MyLib.dll --json           # any of the above as JSON
dotsider analyze MyLib.dll --types -o out.txt  # write to file

CLI: dotsider sessions

Interact with running dotsider TUI instances. Each instance exposes a Unix domain socket for programmatic access.

dotsider sessions list                          # list running instances
dotsider sessions info <pid>                    # assembly info + current view
dotsider sessions view <pid>                    # current tab and view state
dotsider sessions navigate <pid> <tab>          # switch to tab (0-7)
dotsider sessions capture <pid> --format svg    # capture screen (text/ansi/html/svg)
dotsider sessions trace start <pid>             # start tracing the loaded assembly
dotsider sessions trace events <pid>            # get JIT, GC, exception events
dotsider sessions trace counters <pid>          # get performance counters
dotsider sessions trace output <pid>            # get stdout/stderr from traced process
dotsider sessions trace stop <pid>              # stop the active trace

CLI: dotsider agent

MCP server management and AI skill file generation.

dotsider agent mcp                              # launch the dotsider MCP server
dotsider agent init --ai claude                 # generate skill file for a provider
dotsider agent init --path ./SKILL.md           # write to an explicit path
dotsider agent init --stdout                    # print skill content to stdout

Supported --ai providers: claude, gemini, copilot, cursor-agent, opencode, codex, windsurf, kilocode, amp, qwen. Each resolves to the provider's conventional skill path relative to the current directory.

Keyboard

Hex Dump tab uses vi-style modal editing — the editor starts in normal mode (read-only) to prevent accidental writes:

In insert mode, type two hex digits (0-9, a-f) to overwrite one byte. The first digit sets the high nibble; the second commits the edit. Saving validates the PE image before writing — invalid edits are rejected.

Diff mode adds f to cycle filters (All / Added / Removed / Changed).

How it works

dotsider reads assemblies using APIs that ship with the .NET runtime itself — no third-party analysis libraries needed:

• System.Reflection.Metadata provides MetadataReader for traversing the metadata tables (types, methods, references, custom attributes, string heaps)
• System.Reflection.PortableExecutable provides PEReader for the PE structure (COFF header, sections, CLR header, method bodies)
• System.IO.Compression handles NuGet packages (which are just ZIP files containing a .nuspec manifest and DLLs)

The dynamic analysis tab uses Microsoft.Diagnostics.NETCore.Client to connect to a running .NET process via EventPipe — the same diagnostic infrastructure that powers dotnet-trace and dotnet-counters. It launches your assembly with a reverse-connect diagnostic port, so events are captured from the very first instruction.

The TUI is built on Hex1b, a .NET terminal UI library with a React-inspired declarative API, constraint-based layout, theming, and efficient widget reconciliation.

MCP server

dotsider-mcp is a standalone Model Context Protocol server that exposes dotsider's analysis engine to AI coding assistants like Claude Code, VS Code Copilot, and others.

Install

dotnet tool (recommended)

dotnet tool install -g Dotsider.Mcp

Homebrew (macOS / Linux)

brew install willibrandon/tap/dotsider-mcp

WinGet (Windows)

winget install willibrandon.dotsider-mcp

Scoop (Windows)

scoop install dotsider-mcp

Download binary

Grab a standalone binary from Releases.

Configure

Add to your MCP client configuration (e.g. .mcp.json for Claude Code):

{
  "mcpServers": {
    "dotsider": {
      "command": "dotsider-mcp"
    }
  }
}

What it provides

28 tools across assembly analysis, IL disassembly, metadata inspection, dependency graphs, size analysis, string extraction, diffing, NuGet package analysis, and runtime tracing. Tools work in two modes:

• Direct mode — pass an assembly path, get results (no TUI needed)
• Session mode — connect to a running dotsider TUI instance via Unix domain socket for live state, tracing, and navigation

4 guided prompts for common workflows: security audit, API surface review, breaking change detection, and dependency health analysis.

Project structure

src/Dotsider.Core/
  Analysis/           PE reading, metadata extraction, IL disassembly,
                      diffing, dependency graphs, size analysis, runtime tracing
  Analysis/Models/    Data types for analysis results
  Protocol/           Request/response types and JSON options for the UDS protocol

src/Dotsider/
  Commands/           CLI subcommands (analyze, sessions, agent)
  Diagnostics/        Unix domain socket listener for TUI state access
  Infrastructure/     Output formatting, session discovery
  Views/              One file per tab — widget trees built each frame
  DotsiderApp.cs      Main app shell (tab panel, key bindings, hints bar)
  DotsiderState.cs    All mutable UI state in one place
  DiffApp.cs          Diff mode shell
  NuGetApp.cs         NuGet mode shell
  Program.cs          CLI entry point and mode routing

src/Dotsider.Mcp/
  Tools/              MCP tool classes (assembly, IL, metadata, deps, size, etc.)
  Prompts/            Guided analysis prompts (security, API review, breaking changes)
  Program.cs          MCP server entry point (stdio transport)

samples/
  HelloWorld/         Minimal console app
  ComplexApp/         Async pipeline with embedded resources
  RichLibrary/        Library with NuGet deps (Newtonsoft.Json, System.Text.Json)
  RichLibraryV2/      Same library with deliberate API changes (for diff testing)
  MinimalApi/         ASP.NET Core minimal API (web SDK, hosted entry point)
  NativeLib/          Unsafe code, P/Invoke, pointer operations
  EmptyLib/           Minimal library (edge case testing)

tests/Dotsider.Tests/
  SampleAssemblyFixture.cs   Builds all 7 samples once, shared across tests
  *Tests.cs                  Integration tests against real assemblies

tests/Dotsider.Mcp.Tests/
  McpServerTestBase.cs       In-memory MCP server setup for testing
  *Tests.cs                  MCP tool and prompt integration tests

Testing

dotnet test

Integration tests run against real .NET assemblies. The test fixture builds all sample projects automatically. First run takes longer due to NuGet restore; subsequent runs use cache.

Samples

Build the sample assemblies to have something to analyze:

dotnet build samples/RichLibrary
dotsider samples/RichLibrary/bin/Debug/net10.0/RichLibrary.dll

Try diff mode with the two library versions:

dotnet build samples/RichLibraryV2
dotsider diff \
  samples/RichLibrary/bin/Debug/net10.0/RichLibrary.dll \
  samples/RichLibraryV2/bin/Debug/net10.0/RichLibrary.dll

License

MIT