ast-grep vs Moderne

ast-grep is a free, open-source tool for structural code search, linting, and rewriting. It matches patterns against syntax-tree nodes, helping developers locate and change code across a codebase rather than searching plain text. Its CLI can preview and apply rewrites interactively, and scan configurable YAML rules with error, warning, info, or hint severity. Rules can combine pattern, kind, regex, relational, and composite conditions, and CLI commands help create and snapshot-test them. The project says it supports more than 20 languages and can load custom languages. JavaScript and WebAssembly APIs allow programmatic syntax-tree work; a browser playground offers a way to try patterns without local installation. Editor options include a VS Code extension and language-server setups, including for Vim and Neovim. The tool is free, has a web interface, and is distributed through package managers or built from source. Its FAQ notes that some advanced static-analysis information is unsupported, and one rule cannot target multiple languages at once.

Moderne provides infrastructure for developers and AI coding agents to analyze, modernize, secure, and govern large software systems. Its hybrid SaaS runs deterministic recipes across thousands of repositories in a single-tenant cloud environment chosen by provider and region. Moderne DX instead runs within a customer network without outbound connectivity, keeping source code, recipes, and analysis inside that perimeter. Teams can group repositories by business unit and reporting structure using one CSV file, with results rolling up to leaders. DevCenter tracks upgrade, migration, and vulnerability status, including timelines and remaining occurrences. Its marketplace has thousands of type-aware recipes, and changesets support reviewing diffs, viewing results, and making multi-repository commits or pull requests. Changelog connects to source-control services and internal systems; agents can query change context through MCP and the GraphQL API. The product supports Linux, macOS, Windows, web, API, and self-hosted deployments. Pricing is paid, from $2,000/mo. Listed plans include Member at $2,000 a month, billed monthly or yearly; Commercial at a price agreed with the maker; Steering Committee at a price agreed with the maker; Enterprise at a price agreed with the maker; and Fully Managed Service at a price agreed with the maker. Moderne states it is SOC 2 Type 2 compliant.