Why Synth?

The Problem

Existing AST tools are slow and fragmented:

• unified/remark: Popular but 50-3000x slower
• Babel: JavaScript-only, heavy
• tree-sitter: Great but requires native bindings
• Each language has different AST formats: No universal interface

The Solution

Synth provides:

1. Blazing Performance

Pure TypeScript, no native dependencies, yet 50-3000x faster than unified:

Operation	Synth	unified	Speedup
Parse small (1KB)	0.001 ms	0.10 ms	92x
Parse medium (3KB)	0.005 ms	0.58 ms	520x
Parse large (10KB)	0.03 ms	3.50 ms	3154x

How? Arena-based storage, flat arrays, no pointer chasing.

2. Universal AST

One BaseNode interface for ALL languages:

// Same structure for Markdown, JavaScript, HTML, JSON, etc.
interface BaseNode {
  id: NodeId
  type: string
  span?: Span
  parent: NodeId | null
  children: NodeId[]
  data?: Record<string, unknown>
}

Write tools once, use everywhere.

3. 19+ Languages

Category	Languages
Web	HTML, CSS, JSX, Vue
Programming	JS/TS, Python, Go, Rust, Java, PHP, Ruby, C
Data	JSON, YAML, TOML, INI, XML
Query	SQL, GraphQL
Binary	Protocol Buffers, MessagePack
Docs	Markdown (with GFM)

4. Zero Dependencies

Core library has zero runtime dependencies. Minimal bundle size.

5. Incremental Parsing

Token-level incremental updates for real-time editing:

• 99%+ token reuse
• <1ms response time
• 10-100x faster than full re-parse

6. Rich Tooling

• Formatters: @sylphx/synth-js-format
• Minifiers: @sylphx/synth-js-minify
• Linters: @sylphx/synth-lint
• Metrics: @sylphx/synth-metrics
• Docs: @sylphx/synth-docs

When to Use Synth

✅ Good fit:

• AST-based document chunking for RAG
• Code analysis and metrics
• Cross-language tooling
• Real-time editors
• High-performance parsing pipelines

❌ Consider alternatives:

• Need full spec compliance (use official parsers)
• Building compilers (use language-specific tools)
• Need source maps (not yet supported)

Comparison

Feature	Synth	unified	Babel	tree-sitter
Speed	⚡⚡⚡	⚡	⚡⚡	⚡⚡⚡
Languages	19+	Markdown	JS/TS	100+
Universal AST	✅	❌	❌	❌
Pure JS/TS	✅	✅	✅	❌
Incremental	✅	❌	❌	✅
Bundle size	Small	Medium	Large	Large