Ducto is an open-source, modular, and declarative transformation engine designed to manipulate structured data (JSON-like objects) using simple, embeddable, and powerful instructions.

Ducto aims to bridge the gap between raw event streams, ETL pipelines, and dynamic data-driven systems by providing a flexible Domain Specific Language (DSL) that allows you to:

• Filter, mutate, and reshape incoming data
• Perform conditional logic, mappings, and transformations
• Integrate seamlessly into any Go-based CLI, service, or pipeline

• ⚙ Composable - Build complex transformations by combining small, understandable instructions
• 🚀 Optimized for Real-World ETL - Designed to handle event streams, API payloads, and telemetry data at scale
• 📦 Lightweight - Single-purpose library with minimal dependencies
• ✅ Testable - Full suite of unit, integration, and end-to-end tests
• 🟣 Extensible - Designed with operators and instructions as first-class citizens
• 🌐 OpenTelemetry Ready - Hooks for observability without polluting your logic
• 🟢 Serverless-First - Ducto is designed to run:
  • Locally as a CLI
  • Inside serverless environments (Cloud Run, Lambda, etc.)
  • Or embedded directly into your services

• Declarative instruction set
• DSL versioning & strict validation
• Conditional logic (if, exists, and, or)
• Array mapping (map)
• Simple operators (set, copy, delete, replace, merge)
• JSON conversion operators (to_json, from_json)
• Error handling modes (fail, ignore, collect)
• Pluggable metrics and observability (optional)

Ducto is intended to grow into a:

1. High-quality open-source toolkit for data transformation and processing
2. Foundation for more advanced tools:
   • Event stream processors
   • Feature-flag aware routing engines
   • Policy-driven data transformers
   • Real-time telemetry augmentation
3. Building block for the Ducto Project Ecosystem including:
   • Ducto Transformer
   • Ducto Feature Flag Engine
   • Ducto Stream Orchestrator

# Install
go install github.com/tommed/ducto-dsl@latest

# Lint
ducto-dsl lint examples/instructions.json

# Run
echo '{"foo": "bar"}' | ducto-dsl examples/instructions.json

Full DSL specification is available in specs.md.

Ducto is part of an ongoing open-source initiative by @tommed to bring high-quality, composable, and reusable components to data processing pipelines and system integration workflows.

• Code is all licensed under MIT
• Logos/Illustrations are Copyright 2025 Tom Medhurst, all rights reserved.

• ✅ First-class Feature Flag integration
• ✅ Stream orchestrator service
• ✅ Optional OTLP / Prometheus telemetry support
• ✅ Ready-to-deploy serverless bundles