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
dotnet tool install -g dotsider
brew install willibrandon/tap/dotsider
winget install willibrandon.dotsider
scoop bucket add dotsider https://github.com/willibrandon/scoop-bucket
scoop install dotsider
Grab a standalone binary from Releases.
dotsider opens .NET DLLs, EXEs, and supported .wasm outputs and lets you explore them across 8 tabs. Apphost executables are handled as first-class inputs: when an .exe has no .NET metadata, dotsider offers to open the companion managed .dll. Self-contained single-file apps work too — dotsider reads the bundle, extracts the entry assembly, and analyzes it directly.
Native AOT binaries get native treatment instead of an empty metadata view. dotsider validates the embedded ReadyToRun header, walks the runtime sections, surfaces imports, exports, load config, recovered AOT types, recovered methods, and frozen string literals, then renders native disassembly for every .NET architecture it recognizes: x64, Arm64, x86, Arm32/Thumb-2, RISC-V64, LoongArch64, and Wasm32.
When the Native AOT build tree is available, dotsider can attach the pre-ILC managed assemblies plus their mstat/DGML sidecars. That fills the metadata tabs from the original managed inputs and shows each method's IL beside its native code.
ReadyToRun (crossgen2) images keep their full managed metadata, and dotsider joins that metadata to the precompiled method bodies in the same file or composite image. You can see IL beside native code, named call targets from import tables, and component assemblies followed in both directions.
Browser-wasm outputs split into two useful views. Point dotsider at dotnet.native.wasm and it parses the runtime module's Wasm sections, type/table/memory/global declarations, imports, exports, element and data segments, function bodies, and dotnet.native.js.symbols, then renders Wasm32 disassembly with direct-call targets and typed operands named from the same indexes the runtime uses. Point it at a Webcil app assembly such as WasmConsole.wasm and it unwraps the managed metadata and IL instead of treating the container as runtime code.
| Tab | What you see |
|---|---|
| 1 General | Assembly identity, target framework, architecture, dependency table. Press Enter on a reference to drill into it. |
| 2 PE/Metadata | COFF headers, CLR header, PE/Wasm sections, TypeDefs, MethodDefs, AssemblyRefs, custom attributes, resources, debug directory, native imports, exports, load config, ReadyToRun sections, recovered AOT types, and native/Wasm symbols. Press g on a TypeDef or MethodDef to jump to its IL. |
| 3 IL / Native | The label reflects the loaded image: IL Inspector for managed IL, Disassembly for native-only views, and IL + Native when IL is paired with native code. Managed assemblies show a namespace/type/method tree with IL disassembly, PDB source spans, Source Link markers, locals, go-to-definition, and hex jumps. Native AOT binaries and raw Wasm modules list recovered functions and render real disassembly for x64, Arm64, x86, Arm32/Thumb-2, RISC-V64, LoongArch64, and Wasm32 with named call/branch/data targets, Foo+0x12, loc_… labels, MODULE!Function imports, and Wasm function-index calls. ReadyToRun images keep the managed tree, mark precompiled methods, and show IL beside native ranges (hot, funclets, cold). Attached pre-ILC sidecars do the same for Native AOT methods. |
| 4 Strings | User strings, metadata strings, raw ASCII and UTF-16 binary scans, and frozen AOT string literals, with configurable minimum length. |
| 5 Hex Dump | Hex editor with vi-style modal editing (read-only by default), byte category coloring, data interpretation panel, jump-to-offset, and vim navigation. |
| 6 Dep Graph | Visual dependency graph — your assembly at the root, references as nodes, edge weights by TypeRef count. Press Enter on a node to open that assembly. |
| 7 Size Map | Treemap of code size — Assembly > Namespace > Type > Method, sized by IL byte count. Click to drill in; Enter on a method leaf jumps to its IL. |
| 8 Dynamic | Launch the assembly and trace it live via EventPipe — GC events, JIT compilations, exceptions, performance counters, stdout. Press Enter on a JIT event to jump to that method's IL. |
dotsider diff v1.dll v2.dll # side-by-side assembly comparison
dotsider diff before.mstat after.mstat # Native AOT size diff — delta treemap of two builds
dotsider package.nupkg # browse NuGet package contents, inspect any DLL inside
Requires .NET 10 SDK.
dotnet build
The binary lands at src/Dotsider/bin/Debug/net10.0/dotsider.
dotsider <assembly.dll|.exe|.wasm> # TUI mode — interactive assembly/native module explorer
dotsider <package.nupkg> # TUI mode — browse NuGet package contents
dotsider diff <left> <right> # TUI mode — assembly comparison; AOT size diff for mstat inputs
dotsider analyze <file> [opts] # CLI mode — headless analysis to stdout or file
dotsider size-check <target> # CLI mode — AOT size regression report and CI budget gate
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
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 MyAotApp.exe --symbols # list native symbols (Native AOT / native binaries)
dotsider analyze MyAotApp.exe --disasm 'Program.<Main>$' # disassemble a native function (name or 0xVA)
dotsider analyze MyAotApp.exe --correlate # correlate with pre-ILC assembly (counts)
dotsider analyze MyAotApp.exe --correlate Type.Method # IL and native code side by side (name or 0xVA)
dotsider analyze MyR2RApp.dll --r2r-correlate # ReadyToRun stats (precompiled methods, composite)
dotsider analyze MyR2RApp.dll --r2r-correlate Type.Method # IL beside precompiled native (name or 0xVA)
dotsider analyze dotnet.native.wasm --symbols # list SDK Wasm function symbols
dotsider analyze dotnet.native.wasm --disasm 0x1234 # disassemble a Wasm function body
dotsider analyze MyLib.dll --embedded-source Type.Method # print embedded source
dotsider analyze MyLib.dll --deps # assembly references
dotsider analyze MyLib.dll --strings # extract strings
dotsider analyze MyLib.dll --fields # list field definitions
dotsider analyze MyLib.dll --size # size breakdown
dotsider analyze MyLib.dll --bundle # show single-file bundle manifest
dotsider analyze MyLib.dll --json # any of the above as JSON
dotsider analyze MyLib.dll --types -o out.txt # write to file
dotsider analyze MyApp.exe # apphost .exe → auto-redirects to MyApp.dll
dotsider analyze MyApp # single-file bundle → extracts and analyzes entry assembly
Native AOT size-regression checking for CI: compare a build against a baseline via their
mstat size reports (IlcGenerateMstatFile), enforce size budgets, and exit non-zero when one
breaks. Inputs are bare .mstat files or AOT binaries with the sidecar beside them.
dotsider size-check out/pr/app --baseline baseline/app.mstat # delta report, exit 0
dotsider size-check out/pr/app --baseline baseline/app.mstat \
--budget total:growth=1% --budget ns=MyApp.Generated:growth=0 # gate: exit 2 on breach
dotsider size-check out/pr/app --baseline baseline/app.mstat \
--format markdown --summary-file "$GITHUB_STEP_SUMMARY" # GitHub step summary
dotsider size-check out/pr/app --budget max=25mb # absolute cap, no baseline
Budgets: [scope:]limit(,limit)* — scope total / ns=<Namespace> (covers sub-namespaces) /
asm=<Assembly>; limits max=SIZE and growth=SIZE|PERCENT (25mb, 10kb, 1%).
--budget-file adds a JSON document whose object entries carry names, descriptions,
severity: "warning" (reported, never fails), and per-budget contributor counts. --why
attaches the ILC dependency chain for top added contributors. Exit codes: 0 pass, 1 error,
2 budget exceeded.
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 (1-8)
dotsider sessions capture <pid> # capture screen as plain text
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
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.
| Key | Action |
|---|---|
1-8 |
Switch tabs |
Enter |
Drill into selected item (assembly ref, method, DLL in package) |
Esc |
Go back (assembly stack, breadcrumb, or cross-view jump) |
y |
Yank (copy) — selected text in editors, or focused row in tables |
yy |
Yank entire line under cursor |
V |
Select entire line under cursor |
iw |
Select inner word (vim text object) |
iW |
Select inner WORD (whitespace-delimited — grabs fully-qualified names) |
yiw / yiW |
Select + yank word/WORD in one motion |
Tab |
Cycle focus between info panels and tables |
Enter / gd |
Go to definition (tab 3 IL/native view, cursor on a token-bearing instruction) |
g |
Go to tab 3 for the focused TypeDef/MethodDef (PE/Metadata tab) |
u |
Copy Source Link URL from a [source link] marker in tab 3's IL view |
x |
Jump to method body in Hex Dump (tab 3, when a file-backed method or symbol is selected) |
/ |
Search (highlights matches inline) |
n / N |
Next / previous search match |
s |
Toggle human-readable sizes |
q |
Quit |
Info panels (Assembly Info, PE Headers, CLR Header, detail popups, string details) are selectable read-only editors. Click or Tab into them, select text with Shift + arrow keys, and press y to copy. For word-level selection without the mouse, iw selects the word under the cursor and iW selects the full whitespace-delimited token — yiw copies it in one keystroke. V selects the entire line and yy copies the entire line in one motion.
Hex Dump tab uses vi-style modal editing — the editor starts in normal mode (read-only) to prevent accidental writes:
| Key | Mode | Action |
|---|---|---|
i |
Normal | Enter insert mode (enables byte editing) |
Esc |
Insert | Return to normal mode |
h j k l |
Normal | Vim-style cursor movement |
g |
Normal | Jump to hex offset |
e |
Normal | Toggle endianness (LE/BE) |
Ctrl+T |
Any | Toggle text/hex search mode |
Ctrl+S |
Normal | Save edited bytes (only when modified) |
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). The size-diff view (mstat inputs) adds Grown and Shrunk to the filter cycle, Enter/Esc to drill and back out of the delta treemap, w for the dependency chain that keeps an entry in the binary (aggregate tiles show representative child chains; press again to flip sides on a changed entry), and d to disassemble a method's native body. NuGet mode uses Esc to return from DLL inspection to the package browser.
dotsider starts with the low-level APIs that ship with .NET, then layers its own readers on top for the binary formats the runtime libraries do not expose directly:
System.Reflection.MetadataprovidesMetadataReaderfor traversing ECMA-335 metadata tables (types, methods, references, custom attributes, string heaps)System.Reflection.PortableExecutableprovidesPEReaderfor PE structure (COFF header, sections, CLR header, method bodies)- Custom Native AOT, ReadyToRun, WebAssembly, and Webcil readers parse RTR section tables, recovered NativeFormat metadata, frozen objects, mstat/DGML sidecars, native symbols, precompiled method maps, Wasm standard/custom sections, function bodies, SDK symbol maps, and managed
.wasmapp payloads - From-scratch native decoders render AOT, R2R, native, and Wasm code for x64, Arm64, x86, Arm32/Thumb-2, RISC-V64, LoongArch64, and Wasm32
System.IO.Compressionhandles NuGet packages (which are just ZIP files containing a.nuspecmanifest 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.
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.
dotnet tool install -g Dotsider.Mcp
brew install willibrandon/tap/dotsider-mcp
winget install willibrandon.dotsider-mcp
scoop install dotsider-mcp
Grab a standalone binary from Releases.
Add to your MCP client configuration (e.g. .mcp.json for Claude Code):
{
"mcpServers": {
"dotsider": {
"command": "dotsider-mcp"
}
}
}50 tools across assembly analysis, IL disassembly, native disassembly, Native AOT analysis, portable PDB debug info, metadata inspection, dependency graphs, size analysis, size diffing and budget gating, string extraction, diffing, NuGet package analysis, single-file bundle reading, 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
5 guided prompts for common workflows: security audit, API surface review, breaking change detection, dependency health analysis, and single-file bundle inspection.
src/Dotsider.Core/
Analysis/ PE reading, metadata extraction, IL disassembly, diffing,
dependency graphs, size analysis, runtime tracing,
single-file bundle reading, .NET shared framework discovery
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
SizeDiffApp.cs Size-diff mode shell (Native AOT mstat pairs)
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
EmbeddedSourceLib/ Embedded portable PDB source fixture
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)
NetFxConsole/ .NET Framework 4.8 console app (Dynamic tab guard testing)
NativeAotConsole/ NativeAOT-published console app (Dynamic tab tracing tests)
NativeAotConsoleV2/ Same app rebuilt with deliberate size deltas (AOT size-diff fixture)
SelfContainedConsole/ Self-contained single-file bundle (bundle reading, resolution tests)
Dotted.Name.App/ Console app with a dotted assembly name (apphost detection)
NetFxBindingRedirects/ .NET Framework 4.8 fixture for the netfx binder — GAC, framework
runtime dir, binding redirects, codeBase, privatePath, satellite culture.
Five sibling projects (OldDep, NewDep, PrivatePathLib, CodeBaseLib,
CulturedLib) supply the references the root EXE deploys and resolves.
tests/Dotsider.Tests/
SampleAssemblyFixture.cs Builds every sample once and runs the netfx oracle EXE,
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
dotnet test
Integration tests run against real .NET assemblies. The test fixture builds all sample projects automatically, including cross-RID ReadyToRun publishes for architecture-specific native decoder coverage when the SDK has the required packs. First run takes longer due to NuGet restore; subsequent runs use cache.
Native-disassembly goldens are regenerated explicitly with the .NET file-based oracle tool:
dotnet run --file ./scripts/Capture-DisasmOracle.cs -- -Architecture riscv64 -Fixture path/to/blob.bin -OraclePath llvm-objdump -OutputDirectory artifacts/oracles/disasm -- -D -b binary -m riscv:rv64 path/to/blob.binSet DOTSIDER_RUNTIME_ROOT when the runtime clone is not at D:\SRC\runtime. The tool records the oracle command, SDK version, runtime commit, and normalized output beside the golden so decoder changes stay reviewable. See scripts/README.md for the build-first form used by automation.
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
Try the Native AOT size diff with the two AOT builds (publishes with ILC — takes a minute):
dotnet publish samples/NativeAotConsole -c Release
dotnet publish samples/NativeAotConsoleV2 -c Release
dotsider diff \
samples/NativeAotConsole/bin/Release/net10.0/<rid>/publish/NativeAotConsole.mstat \
samples/NativeAotConsoleV2/bin/Release/net10.0/<rid>/publish/NativeAotConsole.mstat
MIT