SECURITY ATLAS / EVALUATION BRIEF Semgrep AppSec Platform Research reviewed: 2026-10-18 https://atlasofsecurity.com/landscape/vendors/semgrep/ THE ATLAS TAKE Semgrep combines source analysis with separately scoped supply-chain and secret capabilities, while its rule system lets teams express security patterns relevant to their own code. Atlas analysis: it is particularly interesting when a security team wants understandable findings and the ability to encode local engineering conventions. The evaluation should distinguish the community engine, commercial analysis, and platform workflow rather than treating them as equivalent. Customizability brings ownership: somebody must test rules, manage exceptions, and prevent broad patterns from overwhelming developers with findings they cannot use. SCOPE Community Edition versus paid rule quality, lockfile layout for supply-chain results, and interfile analysis on monorepos are the main tests. Community Edition is SAST patterns; composition reachability, secrets, and SBOM are platform features and should not be assumed in the free engine. WORTH A LOOK WHEN Teams investing in source-level security rules and developer feedback across one or more CI environments. THINK TWICE WHEN The organization expects custom rules to remain accurate without maintenance or assumes all commercial analysis exists in the community engine. IMPLEMENTATION 1. Select a narrow policy set Choose issues the development team understands and can remediate. 2. Test a custom rule Include positive, negative, and framework-specific cases in a versioned rule fixture. 3. Roll out with ownership Observe findings before blocking; assign maintainers for rules, exceptions, and integration health. OPERATING REALITY Rules, language coverage, scan mode, CI credentials, and finding policy require ongoing attention. Atlas analysis: start with a small, high-confidence policy set and test it against both vulnerable and legitimate examples. Expanding a ruleset is useful only if finding ownership and remediation capacity expand with it. COMMERCIAL CONSIDERATIONS Confirm purchased products, contributor counting, and platform capabilities; include rule maintenance and CI capacity in the operating estimate. - Code, Supply Chain, and Secrets entitlement - Contributing developers and repository rollout - CI capacity and rule-maintenance effort EVALUATION PLAN / PROPOSED TESTS, NOT COMPLETED RESULTS 1. Validate a custom rule Acceptance evidence: Retain fixtures showing the intended flaw is found and legitimate code remains unflagged. Owner: __________ Pass criterion: __________ Observed result: __________ Evidence location: __________ 2. Compare full and change scans Acceptance evidence: Scan the same branch and revision with the planned modes and explain baseline differences. Owner: __________ Pass criterion: __________ Observed result: __________ Evidence location: __________ 3. Trace dependency context Acceptance evidence: Verify a known dependency path and document any reachability result that remains unknown. Owner: __________ Pass criterion: __________ Observed result: __________ Evidence location: __________ QUESTIONS FOR THE VENDOR - Which rules fire on Community Edition versus the Pro engine on this monorepo? - Does lockfile layout support supply-chain reachability, or are package relationships missing? - Is interfile analysis complete enough on the repository layout the team actually uses? EVIDENCE GAPS - No independent false-positive or language-coverage benchmark was performed. - Commercial engine behavior and dependency reachability require representative code validation. SOURCES Writing Semgrep rules (Documentation) https://docs.semgrep.dev/writing-rules/overview Semgrep Code overview (Documentation) https://docs.semgrep.dev/semgrep-code/overview Semgrep Supply Chain overview (Documentation) https://docs.semgrep.dev/semgrep-supply-chain/overview Use synthetic fixtures in an authorized environment. Agree rollback and acceptance criteria before enforcement. Documentation research and Atlas analysis. Independent hands-on effectiveness, effort, and complete price remain unassessed.