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.
For organizations with dedicated AppSec functions writing custom security patterns — internal authentication bypasses, framework-specific anti-patterns, regulated-industry sinks — Semgrep's rule engine is a meaningful capability advantage. For teams optimizing for general-purpose quality and security coverage with minimal upfront investment, SonarCloud's built-in breadth wins.
Pricing Models and Onboarding Friction
Semgrep's pricing is per-contributor for the Team tier (around $110 per contributor per month) with module-level charges for Supply Chain SCA and Secrets scanning. Small teams may stay free with Community Edition but hit cross-file analysis and managed-rule limits as they scale. The pricing rewards organizations with a stable contributor count and a clear AppSec module roadmap, but it can become expensive for engineering organizations with rapidly growing headcount.
SonarCloud charges per analyzed lines of code for private repos, starting at roughly $14 per month for 100K LOC. The model is forgiving for small services and brutal for monorepos with large amounts of generated or vendored code — exclusion patterns are essential. Onboarding SonarCloud takes minutes for GitHub-hosted projects and Quality Gates start working immediately. Onboarding Semgrep takes longer because the value depends on having or adopting a useful ruleset; the registry covers a lot, but tuning for a low false-positive rate is real upfront work.
The Bottom Line
SonarCloud is the stronger default for teams that want comprehensive code quality and security feedback with minimal configuration — PR decoration, Quality Gates, technical debt tracking, and broad language coverage make it approachable for the entire engineering organization. Semgrep earns its place when AppSec is a dedicated function inside the team, when custom vulnerability patterns are part of the security program, or when cross-file taint analysis on specific security sinks is the actual requirement. Many mature engineering organizations run both: SonarCloud for organization-wide quality enforcement, Semgrep for targeted AppSec rule authoring on the highest-risk surfaces.