Overview

Instead of matching source text, ast-grep matches patterns against syntax-tree nodes. That lets a search target code structure across variations in formatting, and helps avoid the false matches that blunt text searches can produce. The CLI can preview and apply changes interactively; the project describes parallel Rust processing for searches and replacements across thousands of files. This makes it a good fit for repeatable codebase-wide work, though it should not be mistaken for a tool that understands every behavior or relationship in a program.

Key features

Search, rewrite, and lint

The scan command runs configurable AST-pattern rules and reports severities ranging from error to hint. That gives teams a way to enforce code-shape conventions and surface findings at different levels of urgency. Interactive rewrite previews help reviewers inspect a proposed transformation before applying it. These capabilities suit structural refactors and targeted checks; they are less suitable when a rule depends on advanced static-analysis information that ast-grep does not support.

Custom rules and testing

Rules are written in YAML and can combine pattern, kind, regex, relational, and composite matching conditions. The CLI includes commands to create and test rules, including snapshot-based testing. That combination supports reusable rules with a way to check their expected matches, but teams still need to design and maintain rules for their own code. A single rule cannot target multiple languages at once: use a superset language with languageGlobs or maintain separate rules for each language.

Languages, editors, and APIs

The project says it supports more than 20 languages and can load custom languages, a broad base for polyglot repositories. Its online playground lets users try patterns and rewrite rules without a local installation. Editor support includes a VS Code extension and language-server integrations for editors such as Vim and Neovim; the server publishes diagnostics and diagnostic code actions, with lint diagnostics requiring an sgconfig.yml project file. JavaScript and WebAssembly APIs extend syntax-tree inspection and changes to programs and browser or other WASM environments. The CLI is distributed through npm, Cargo, Homebrew, MacPorts, Nix, and pip, and can also be built from source.

Security examples and support

The example catalog includes rules for issues such as a Go JSON tag vulnerability and C/C++ format-string risks. These examples show how structural rules can target security-relevant code patterns, but do not turn ast-grep into a full security-analysis suite. Users can seek community help through GitHub, Discord, Stack Overflow, and Reddit.

Pricing

ast-grep is open source and free. Its ast-grep plan costs 0.00 USD per free, and there is no free trial because the project is already free to use. There are no paid tiers or seat-based pricing to weigh; the practical trade-off is that users take on the work of setting up and maintaining their rules and workflows.

Platforms

ast-grep is available across Linux, macOS, and Windows, with API and extension support and a web playground. Its codebase indexing scope and self-hosted deployment suit teams that want to run structural search within their own development workflow rather than rely on a hosted code-analysis service.

Who it's for

Choose ast-grep if you need structural code search, linting, or repeatable rewrites across a codebase, especially in a repository spanning multiple languages. It is also a strong option for developers who want to author YAML rules, test them, and connect findings to an editor or programmatic API. Look elsewhere or pair it with another tool when the job depends on advanced static analysis, or when one shared rule must cover multiple languages.

Pros and cons

Pros

Structural matching targets syntax-tree nodes, making it more precise for code-shaped searches and rewrites than plain text matching.
Interactive previews, configurable lint severities, and rule-testing commands support a controlled, repeatable workflow.
More than 20 supported languages, custom-language loading, editor integrations, and JavaScript and WebAssembly APIs offer several ways to fit it into development work.
Free, open-source distribution and multiple package managers make adoption possible without a subscription.

Cons

It lacks some advanced static-analysis information, limiting checks that require more than syntax structure.
Rules cannot target multiple languages at once, so polyglot teams may need separate rules or a superset language configuration.
Lint diagnostics from the language server require an sgconfig.yml project file, adding setup for editor-based linting.

Alternatives

For a different code-search approach, Semantic Designs Source Code Search Engine has a free evaluation version capped at 10,000 lines and supports Java, COBOL, C++, and pseudo-code; consider it when those languages and that evaluation scope fit better. Sourcebot is a freemium API, self-hosted, and web option, while Code Search offers a free Community plan with unlimited users, full-text search, repository find-and-replace, a CLI, and an MCP server. Choose either when those search and deployment details better match your workflow than AST-pattern rules.

OpenGrok is a free, open-source alternative for readers considering another code-search project. Chatterbox TTS is an unrelated text-to-speech option. Code Fundi is a freemium alternative with a paid Dev plan at 21.00 USD per month. searchcode is free during beta, and sqry is a free, local, MIT-licensed option for Linux, macOS, and Windows.

Browse more Code Search Tools or Code Refactoring Tools.

Verdict

ast-grep is a strong choice for developers who need free, reusable structural search, linting, and rewrites across a codebase. Its syntax-aware rules and interactive transformations are the main reasons to choose it; look elsewhere or pair it with deeper analysis when syntax-level matching is not enough, or when rules must span languages in one definition.

	ast-grep	HodorReflexes
Free plan	Yes
Free trial	No
Paid from	Free
Platforms	api, extension, Linux, macOS, Web, Windows
Indexing scope	codebase
Deployment	self_hosted
Regex search	Yes
Code navigation	Yes
IDE extensions	Yes
Free plan		Yes
Supported games		The Elder Scrolls Online (ESO)
Combat metrics		damage_healing
Live overlay		Yes

ast-grep vs HodorReflexes

ast-grep

HodorReflexes