Semgrep
By Semgrep, Inc.
Semgrep is a static analysis tool that scans source code for bugs, security vulnerabilities, and code quality issues using pattern-based rules that look like the code they match, making custom rules easier to write than with traditional…
Definition
Semgrep is a static analysis tool that scans source code for bugs, security vulnerabilities, and code quality issues using pattern-based rules that look like the code they match, making custom rules easier to write than with traditional abstract-syntax-tree-based static analyzers. It supports dozens of programming languages and is used both as an open-source command-line tool and, via Semgrep's commercial offerings, as a managed platform for running rules across an organization's repositories.
Overview
Semgrep exists to make static analysis rule-writing accessible to ordinary developers and security engineers rather than requiring deep expertise in compiler theory or abstract syntax trees. Traditional static analysis tools often require rules to be written against a tool-specific intermediate representation, which is powerful but has a steep learning curve; Semgrep instead lets rule authors write patterns that look almost like the source code being matched, with metavariables acting as wildcards for arbitrary expressions, so a rule detecting an unsafe function call or a common security anti-pattern can be written in minutes rather than requiring specialized static analysis training. Mechanically, Semgrep parses source code into an abstract syntax tree internally, but the rule-writing interface abstracts that away, letting users write rules in a YAML format specifying a pattern to match, along with metavariables like `$X` that bind to any sub-expression. When Semgrep scans a codebase, it matches these patterns structurally against the parsed code rather than against raw text, meaning a rule matches regardless of variable naming or formatting differences that would defeat a simple regular expression, while remaining far simpler to author than a full AST-matching tool built from scratch. Semgrep ships with an extensive registry of community and Semgrep-maintained rules covering common vulnerability classes (SQL injection, path traversal, hardcoded secrets) across many languages, and organizations can write and share custom rules for their own codebase conventions. Within the static analysis landscape, Semgrep sits between simple linters, which check style and basic correctness, and heavier, more expensive commercial SAST (static application security testing) tools like Checkmarx or Veracode, which do deeper data-flow and taint analysis but require more setup and tuning. Semgrep's lighter-weight, pattern-based approach makes it well suited to being run directly in a developer's editor or in CI on every pull request, catching issues early rather than only in a periodic security audit, though its analysis is generally less deep than dedicated taint-tracking SAST engines for cross-function or cross-file vulnerability chains. In practice, Semgrep is used in CI pipelines to block pull requests that introduce known vulnerability patterns, in pre-commit hooks to give developers immediate feedback, and by security teams writing custom rules to enforce organization-specific secure coding standards that generic tools would not catch. Its speed and low false-positive design relative to some legacy SAST tools have made it popular for embedding directly into developer workflows rather than being run as a separate, slower gate late in the release process. The trade-offs are depth versus speed and accessibility. Semgrep's pattern-matching approach is faster to write rules for and faster to run than deep interprocedural taint analysis, but it can miss more complex vulnerabilities that require tracking data flow across multiple functions or files, which dedicated commercial SAST tools are built to handle. Organizations with the highest security assurance requirements often run Semgrep alongside, not instead of, a deeper SAST tool.
Key Features
- Pattern-based rules written to resemble the code they match
- Metavariables act as wildcards matching arbitrary sub-expressions
- Structural matching against parsed code, not raw text or regex
- Extensive registry of community and maintained vulnerability rules
- Supports dozens of programming languages
- Designed to run in editors, pre-commit hooks, and CI pipelines
- Custom rules enforce organization-specific secure coding standards
- Lighter-weight than deep interprocedural taint-tracking SAST tools