semver
The official npm semantic versioning library for Node.js. Parses, validates, compares, and performs range matching on semver version strings. Implements the full Semantic Versioning 2.0.0 spec — handles major.minor.patch, pre-release tags, build metadata, and range operators (^, ~, >=, etc.). Used by npm, yarn, pnpm, and every package manager ecosystem tool to resolve dependency version constraints.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
Pure utility library — no network, no secrets, no auth. ReDoS vulnerability patched in v7.5.2 — ensure using up-to-date version.
⚡ Reliability
Best When
You need to parse, compare, or validate semver version strings in any JavaScript/Node.js tooling, CI scripts, or package management code.
Avoid When
You need a full release automation workflow — use semantic-release or changesets which use semver internally.
Use Cases
- • Validate that a package version string is valid semver before publishing or using in CI/CD pipelines
- • Compare two version strings to determine which is newer for update checks and version enforcement
- • Determine if a specific version satisfies a semver range constraint for compatibility checking in tools
- • Increment version strings (patch/minor/major) programmatically in release automation scripts
- • Parse version strings to extract major, minor, patch components for conditional logic in build scripts
Not For
- • Calendar versioning (CalVer) — semver handles semver only; other versioning schemes need custom parsing
- • Git tag management — use standard-version or semantic-release for automated git tagging workflows
- • Package publishing — use npm publish, np, or semantic-release for full publish automation
Interface
Authentication
No authentication — pure utility library.
Pricing
Fully free, ISC licensed. Maintained by npm/GitHub.
Agent Metadata
Known Gotchas
- ⚠ semver.valid() returns null for invalid semver strings (does not throw) — always null-check the return value before using it
- ⚠ semver.satisfies() range matching treats '^1.0.0' as '>=1.0.0 <2.0.0' — understand the caret/tilde semantics before using for compatibility checks
- ⚠ Pre-release versions (1.0.0-alpha.1) do NOT satisfy range '^1.0.0' by default — must use semver range options or explicit pre-release comparisons
- ⚠ semver.coerce() tolerates non-semver version strings (e.g., '1.0' → '1.0.0') — useful for lenient parsing but be aware it may mask invalid versions
- ⚠ Range comparisons treat '>=1.0.0' and '1.x' equivalently but '^1.0.0' and '~1.0.0' are different — test range strings with semver.validRange() before using
- ⚠ Bundle size: semver is small but transitive dependencies in build tools may include multiple versions — semver.clean() is useful for normalizing version strings from various sources
Alternatives
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Scores are editorial opinions as of 2026-03-07.