Jint is a high-performance JavaScript interpreter for .NET, implementing the full ECMAScript specification (ES2025+) with extensive Web API support (Fetch, Streams, Crypto, Encoding, Workers, etc.) and a headless browser automation layer. The core engine provides a rich embedding API with CLR interop, module loading, execution constraints, and debugging via the Chrome DevTools Protocol. The architecture is modular: the engine itself is a library (Jint), with separate packages for DevTools debugging (Jint.DevTools), browser automation (Jint.Browser), and source generators for efficient interop (Jint.SourceGenerators). The codebase is exceptionally well-tested with thousands of unit tests, Web Platform Tests (WPT), and Test262 conformance tests, plus a comprehensive benchmark suite. It is used in production by projects like RavenDB, EventStore, and OrchardCore as an embedded scripting engine.
Yaegi is a Go interpreter written in Go, designed for embedding scripting capabilities into Go applications, running Go scripts, or providing an interactive REPL. The architecture consists of a core interpreter package (`interp`) that parses Go source code into an AST, performs type checking and control flow graph (CFG) generation, and executes the CFG via a runtime engine. Standard library support is provided through auto-generated reflective wrappers (`stdlib/`) that expose Go's standard library symbols to the interpreter. A command-line tool (`cmd/yaegi`) offers subcommands for running scripts, testing, and extracting stdlib wrappers. The project also includes code generators (`internal/cmd/genop`, `extract/extract.go`) that automate the creation of operator implementations and stdlib bindings. External dependencies are limited to the Go standard library; the interpreter itself has no third-party runtime dependencies. Key entry points are `interp.New()`, `interp.Eval()`, and `interp.Use()` for embedding, and the `yaegi` CLI for standalone use.