Zero-allocation, source-generated structured logging for .NET 10.
Logsmith is a logging framework where the source generator is the framework. Every log method is analyzed at compile time, and the generator emits fully specialized, zero-allocation UTF8 code tailored to your exact parameters. No reflection. No boxing. No runtime parsing of message templates.
| Name | NuGet | Description |
|---|---|---|
Logsmith |  | Runtime library with public types, sinks, and the bundled source generator. Default mode: Shared. |
Logsmith.Generator |  | Thin meta-package. Depends on Logsmith for the generator and build assets only — no runtime DLL. Default mode: Standalone. |
Logsmith.Extensions.Logging |  | Microsoft.Extensions.Logging bridge. Routes ILogger calls through Logsmith sinks. |
Most .NET logging frameworks parse message templates at runtime, box value-type arguments into object[], and dispatch through multiple abstraction layers before bytes reach an output target. For applications where logging sits on the hot path — game engines, trading systems, NativeAOT deployments — those costs are measurable.
Logsmith takes the source-generator approach to its conclusion: the generator does not supplement a runtime framework, it replaces it entirely. It reads your method declarations at build time, knows the concrete types of every parameter, and emits direct UTF8 formatting calls with pre-computed property names and type-specific serialization paths.
| Capability | Logsmith | MEL + LoggerMessage | ZLogger | Serilog | NLog |
|---|---|---|---|---|---|
| Source-generated method bodies | Yes | Yes | Yes | No | No |
| Zero runtime dependency mode | Yes (standalone) | No (requires MEL) | No (requires MEL) | No | No |
| Abstraction mode for libraries | Yes | No | No | No | No |
| Zero allocation hot path | Yes | Partial (MEL infra allocates) | Yes | No | No |
| UTF8 end-to-end | Yes | No (UTF16 strings) | Yes | No | No |
| Structured logging | Yes (Utf8JsonWriter) | Yes | Yes | Yes | Yes |
| Compile-time level stripping | Yes ([Conditional]) | No | No | No | No |
| No boxing of value types | Yes | Yes (generated path) | Yes | No (object[] params) | No (object[] params) |
| No reflection | Yes | Yes | Partial | No (used in enrichers) | No (used in layouts) |
| NativeAOT compatible | Yes | Yes | Yes | Partial | Partial |
| Compile-time diagnostics | Yes (LSMITH001-010) | Yes | Limited | No | No |
| Log sampling / rate limiting | Yes (compile-time) | No | No | No | No |
| Scoped context (AsyncLocal) | Yes (LogScope) | Yes (ILogger.BeginScope) | Yes | Yes (LogContext) | Yes (ScopeContext) |
| Dynamic level switching | Yes (env var, file) | Yes (IOptionsMonitor) | Yes | Yes (LoggingLevelSwitch) | Yes (config reload) |
| Custom type serialization | ILogStructurable | ILogger.BeginScope | IZLoggerFormattable | Destructure policies | Custom layout renderers |
| MEL ecosystem compatibility | Yes (bridge package) | Native | Native | Via Serilog.Extensions.Logging | Via NLog.Extensions.Logging |
| DI container required | No | Typically yes | Typically yes | No | No |
| Transitive dependencies | Zero (standalone) | MEL abstractions | MEL + ZLogger | Serilog + sinks | NLog |
- Zero-allocation logging pipeline — every log call writes directly to sinks with no heap allocation, no boxing, no string interpolation
- Source-generated method bodies — the generator emits fully specialized UTF8 code per log method at compile time
- Compile-time level stripping —
[Conditional]attributes remove log calls below a configured threshold from release builds - Three operating modes — Shared, Standalone, or Abstraction for apps and libraries
- Six built-in sinks — Console, File, Stream, Debug, Recording, and Null with category filtering
- Structured JSON output —
IStructuredLogSinkreceives typed properties viaUtf8JsonWriter - Scoped context enrichment — attach ambient properties via
LogScope.Pushwith zero overhead when inactive - Log sampling and rate limiting — throttle high-frequency log methods with compile-time guards
- Dynamic level switching — adjust log levels at runtime via environment variables or config files
- MEL bridge — route
ILoggercalls through Logsmith sinks withLogsmith.Extensions.Logging - Custom type serialization — implement
IUtf8SpanFormattableandILogStructurablefor optimal formatting - Compile-time diagnostics — template mismatches, missing parameters, and unsupported types caught before runtime
// 1. Initialize at startupLogManager.Initialize(config =>{config.MinimumLevel=LogLevel.Debug;config.AddConsoleSink();config.AddFileSink("logs/app.log",rollingInterval:RollingInterval.Daily);});// 2. Declare log methods[LogCategory("Renderer")]publicstaticpartialclassRenderLog{[LogMessage(LogLevel.Debug,"Draw call {drawCallId} completed in {elapsedMs}ms")]publicstaticpartialvoidDrawCallCompleted(intdrawCallId,doubleelapsedMs);[LogMessage(LogLevel.Error,"Shader compilation failed: {shaderName}")]publicstaticpartialvoidShaderFailed(stringshaderName,Exceptionex);}// 3. Call themRenderLog.DrawCallCompleted(42,1.23);The generator emits fully specialized, zero-allocation UTF8 code for each log method at compile time. See Getting Started for the full walkthrough.
Full benchmark results comparing Logsmith against MEL, Serilog, NLog, and ZLogger are available in docs/benchmarks.md.
This project is licensed under the MIT License.