act101

act101 is a groundbreaking developer tool that fundamentally changes how AI coding agents interact with source code. Unlike traditional AI coding assistants that rely on whole-file rewrites and LLM-generated patches, act101 provides a Model Context Protocol (MCP) server that exposes over 183 Abstract Syntax Tree (AST) aware refactor operations, 30 codebase analyzers, 15 query operations, and 8 porting operations to AI agents. This allows agents to perform precise, language-aware code transformations across 163 programming languages using a single native Rust binary. The tool is designed for professional developers using AI coding environments like Claude Code, Cursor, Codex, and OpenCode. Its main value proposition is enabling AI agents to actually refactor and port code with surgical precision, automatic checkpointing, and instant undo capabilities, rather than simply generating suggestions. The tool operates entirely on the user's machine with no telemetry, no indexing, no caching, and no cold start, ensuring code privacy and immediate responsiveness. It is free for personal use and represents the first dev tool that bridges the gap between AI conversation about code and actual code manipulation.

AST-Aware Refactor Operations

act101 provides 183 typed, AST-aware refactor operations that AI agents can call directly. These include extract-function, rename, move-symbol, inline, convert-to-dataclass, extract-trait, add-type-hints, generate-init, organize-imports, and 174 more. Each operation works across the entire codebase with cross-file consistency, preserving comments, formatting, and structural integrity. Every operation creates an automatic checkpoint, allowing instant undo if the result is unsatisfactory. This represents a massive improvement over traditional whole-file rewrites that often lose developer intent and break existing formatting.

Cross-Language Porting State Machine

The tool includes 8 specialized porting operations that drive end-to-end language migrations through a sophisticated state machine. The process begins with port_contract to anchor source-to-target migration rules, followed by port_inventory to enumerate every symbol that must move, port_order to resolve dependency ordering, and a port_manifest state machine (init, add, update, remove, note) to track progress step by step. This structured approach enables reliable porting between any two of the 163 supported grammars, such as C to Rust, Ruby to Elixir, or COBOL to Java.

Comprehensive Codebase Analyzers

act101 ships with 30 built-in codebase analyzers that provide AI agents with deep structural understanding of the codebase before making any changes. These analyzers cover cohesion, coupling, cycles, chokepoints, hotspots, dead code, layers, seams, clusters, surface area, fan balance, migration readiness, type completeness, and more. The agent receives a complete structural map of the repository, enabling informed decisions about refactoring priorities, migration strategies, and architectural improvements without needing to manually explore the codebase.

Pre-Built Agent Skills

The tool includes 10 pre-built agent skills that compose individual operations into common engineering workflows. These skills include architecture-audit, code-review, refactoring, code-navigation, code-generation, migration-assessment, boundary-analysis, change-impact, health-check, and architectural-refactoring. Developers can invoke these skills using simple commands like /skill-name in their AI coding environment, allowing agents to execute complex multi-step engineering tasks without manual orchestration of individual operations.

Large-Scale Code Refactoring

Engineering teams can use act101 to perform systematic refactoring across massive codebases spanning 163 languages. An AI agent can identify all instances of a deprecated pattern using the codebase analyzers, then execute rename, extract-function, and move-symbol operations across hundreds of files with guaranteed consistency. The automatic checkpointing and instant undo capabilities make this safe for production code, while the AST-aware operations ensure that comments, formatting, and type information are preserved throughout the transformation process.

Cross-Language Migration Projects

Organizations modernizing legacy systems can leverage act101 for automated porting between languages. A team migrating a COBOL banking application to Java can use the porting state machine to systematically enumerate all symbols, resolve dependency ordering, and track progress through the manifest system. The agent handles the mechanical translation while developers focus on business logic validation and architectural decisions. The same approach works for porting C libraries to Rust for memory safety, or Ruby applications to Elixir for improved concurrency.

Architectural Analysis and Improvement

Software architects can use act101 to gain deep insights into codebase structure before making architectural decisions. The 30 analyzers provide comprehensive reports on coupling patterns, dependency cycles, code hotspots, module boundaries, and migration readiness. An agent can identify the most tightly coupled modules, locate dead code that should be removed, and suggest boundary improvements. This data-driven approach enables architects to prioritize refactoring efforts where they will have the greatest impact on maintainability and performance.

Automated Code Review and Quality Assurance

Development teams can integrate act101 into their code review workflow to automate quality checks. When a developer opens a pull request, an AI agent can analyze the changes against the entire codebase, checking for architectural violations, detecting potential regressions in coupling patterns, and verifying that new code follows established module boundaries. The agent can automatically suggest refactoring operations to improve code quality, and the developer can apply these suggestions with a single command, knowing that the changes are AST-aware and will not break existing functionality.

How does act101 ensure code privacy and security?

act101 operates entirely on the user's machine with no telemetry collection and no external data transmission. The single native Rust binary contains no plugin runtime, no package graph, and no supply-chain attack surface. All code parsing, analysis, and transformation happens locally. The only potential external communication is for license verification, which is minimal and clearly stated. Your code never leaves your machine, making act101 suitable for even the most sensitive enterprise codebases.

What AI coding environments are compatible with act101?

act101 is MCP-native and works with any MCP-aware client. This includes Claude Code, Cursor, Windsurf, Codex, and OpenCode. The built-in MCP server exposes all operations directly to these environments, allowing developers to use their preferred AI coding assistant while gaining access to act101's precise, AST-aware capabilities. No additional configuration or plugins are required beyond setting up the MCP server connection.

How does act101 compare to traditional AI code generation tools?

Traditional AI coding tools typically generate whole-file rewrites or patch suggestions that often lose comments, break formatting, and have no undo capability. act101 provides typed, AST-aware operations that preserve code structure and enable instant rollback. It achieves approximately 85% fewer tokens than file-based operations, making it more efficient and precise. Additionally, act101 has no indexing, no caching, and no cold start, meaning results are always current and never stale.

What programming languages does act101 support?

act101 supports 163 programming language grammars in a single binary. This covers virtually all major languages including Python, Rust, TypeScript, Go, Java, C, C++, Ruby, Elixir, COBOL, and hundreds more. The porting operations work between any two supported grammars, enabling cross-language migrations that were previously impractical. The refactor operations and analyzers are designed to work consistently across all supported languages, providing a unified interface for code manipulation regardless of the language being used.

act101 is free for personal use, allowing individual developers to access all 183 refactor operations, 30 codebase analyzers, 8 porting operations, and 10 pre-built agent skills without cost. For commercial and team usage, pricing plans are available through the official website. The free personal tier includes the complete feature set, making it accessible for learning, personal projects, and evaluation. Commercial pricing details can be found on the act101 pricing page, with options designed to scale from individual professionals to large enterprise teams.