What Sets Them Apart
Semgrep and SonarCloud both catch security and quality issues in source code, but they approach the problem from opposite ends. Semgrep is a rule-based static analysis engine built for security engineers who want precise, AST-level patterns and a registry of community rules to extend. SonarCloud is a hosted code quality platform that bundles Quality Gates, PR decoration, technical debt tracking, and 30+ language coverage into one workflow. The choice usually comes down to whether your primary concern is AppSec rule precision or developer-facing quality feedback at scale.
Semgrep and SonarCloud at a Glance
Semgrep is an open-source SAST engine with more than 11,000 GitHub stars, a Community Edition that runs locally for free, and paid Team and Enterprise tiers (starting around $110 per contributor per month) that add cross-file taint analysis, Supply Chain SCA, and Secrets scanning. Rules are YAML patterns that mirror code AST, which lets security teams encode organization-specific vulnerability shapes without learning a new DSL. The engine targets the write-your-own-rules power user and the AppSec function inside engineering organizations.
SonarCloud is the cloud-hosted version of SonarQube, free for public and open-source repositories with paid tiers from $14 per month for 100K lines of analyzed code on private repos. It connects via a GitHub App, GitLab, Azure DevOps, or Bitbucket integration and adds Quality Gates as required pull-request status checks. Coverage spans more than thirty languages with over five thousand built-in rules, and the dashboard surfaces technical debt and historical trend metrics that read well in leadership reviews.
Both tools integrate cleanly with GitHub Actions and similar CI systems, and both are positioned as merge-blocking gates rather than after-the-fact reports. Where they diverge is intent: Semgrep targets bring-your-own-rules precision for security engineers, while SonarCloud targets set-it-and-forget-it coverage for the broader engineering organization.
Custom Rule Authoring vs Built-In Coverage Depth
Semgrep's rule authoring is the product's defining feature. YAML patterns mirror the abstract syntax tree of the target language, which means a security engineer can write a rule for, say, a custom ORM injection sink in an internal framework without learning a parser DSL or fighting regex limitations. The community registry contains over a thousand rules to bootstrap from, and cross-file taint analysis (in paid tiers) lets you express data-flow rules that catch vulnerabilities split across modules.
SonarCloud's coverage is broader by default and shallower in customization. Five-thousand-plus built-in rules across thirty-plus languages mean most teams find useful coverage on day one, including security hotspots that flag code requiring manual review. You can build Quality Profiles that bundle rule activations and severities, but you cannot author a new pattern at the AST level the way Semgrep allows. This is the right trade-off for teams that want predictable coverage without a full-time AppSec engineer.