KCode vs Semgrep, CodeQL, Snyk Code, SonarQube

Five SAST tools, five philosophies. KCode's pitch: fewer false positives (LLM-verified), deterministic one-command fixes, and source that truly never leaves your machine.

Last updated 2026-04. Features change — the axes below are what we think matter. Counter-evidence welcome.

Core philosophy

KCode

Scanner + verifier

Deterministic regex + AST scanner. Small local LLM verifies each candidate to strip FPs. /fix ships patches, not just flags.

Semgrep

Rule-based scanner

~2000 OSS rules + commercial catalog. Lightweight, fast, great community. Optional cloud dashboard (Semgrep Cloud Platform).

CodeQL

Dataflow queries

GitHub-owned. Strongest dataflow analysis of the five — can chase a taint across a codebase. OSS-research license.

Snyk Code

DeepCode + SCA

Integrated platform: SAST + SCA + IaC + container. Commercial polish. Uses a hosted model for analysis.

SonarQube

Quality + security

Legacy code's best friend. Strongest on code smells, tech debt, and coverage metrics. Self-host or cloud.

Feature comparison

KCode column in cyan. Columns are alphabetical after that. Em-dash = not a product goal.

FeatureKCodeCodeQLSemgrepSnyk CodeSonarQube
Pricing (team of 10 devs)$0 (AGPL) or $190/mo Pro$0 (GH Advanced Security for OSS / $49/committer/mo private)$0 (OSS) or $400/mo (Team)$580/mo ($58/dev)$1,500/yr (Developer), self-host
Source ever leaves your machine?No — scanner + verifier both localCLI local; dashboard cloudCLI local; Cloud Platform optionalYes — hosted analysis engineNo (self-host) / Yes (SonarCloud)
LLM-verified findingsYes — strips FPs before they reach the reportUses DeepCode AI (cloud-side)
Auto-fix (not just flag)/fix — deterministic patches per patternautofix on select rulesDeepCode AI Fix (cloud)
Tokens / cost per run~10k (local LLM)N/A (dataflow, no LLM)N/AOpaque (hosted)N/A
Rule / pattern count256 curated3,000+ queries2,000+ OSS rulesNot published3,000+ rules (security + quality)
Languages covered20+ (C, Rust, Go, Python, Java, JS, …)~10 (C/C++, C#, Go, Java, JS/TS, Python, Ruby, Swift)30+~1530+
Output formatSARIF v2.1.0 + MarkdownSARIFSARIF + JSONSARIF + JSONSARIF (via plugin) + internal
CI integration (one-line)GitHub ActionGitHub Action (native)GitHub Action + CLIGitHub Action + CLIPlugin per CI
LicenseAGPL-3.0 (dual-license available)Proprietary; free for OSS researchLGPL-2.1 (rules often Commons Clause)ProprietaryLGPL-3.0 (Community) / Commercial
NASA-validatedPR #107 on nasa/IDF

Numbers

256
curated patterns
hand-written + fixture-tested on every release
~10k
tokens per audit
scanner pre-filter → local LLM verifier
28
real bugs found in NASA IDF
pointer arithmetic, unreachable code, resource leaks

From code to PR in three commands

# Inside the KCode TUI
❯ /scan project/
→ 256 patterns scan, LLM-verified, AUDIT_REPORT.md + AUDIT.sarif
❯ /fix project/
→ Deterministic patches applied (size guards, bounded copies, RAII wrappers)
❯ /pr project/
→ Branch + commit + LLM-generated PR description grounded in finding evidence

When to choose what

KCode

Privacy-critical codebases, air-gapped dev, teams tired of FP noise, C/Rust/Go-heavy repos, bring-your-own-hardware economics.

CodeQL

You need deep dataflow across a huge codebase. Complex taint analysis. Already on GitHub Advanced Security.

Semgrep

You want to write your own rules in a familiar syntax. Polyglot monorepos. CI-as-code culture.

Snyk Code

You want one vendor for SAST + SCA + IaC + container. Compliance / SOC2 reporting built-in.

SonarQube

Legacy codebase quality + security together. Coverage + duplication + smells + CWE in one dashboard.

What KCode is NOT (yet)

Not a dataflow engine. CodeQL wins on cross-function taint tracking. KCode is regex + AST + semantic guards + LLM verification — it catches the 256 bug classes it knows about, but it won't trace a tainted string across 15 functions.

Not a compliance suite. Snyk and SonarQube have polished SOC2 / PCI / GDPR reporting. KCode emits SARIF; if your auditor wants a branded dashboard, use one of those instead (or on top).

Not the largest rule catalog. Semgrep has ~2,000 OSS rules; KCode has 256 curated ones. We chose depth over breadth — every KCode pattern ships with positive + negative fixtures and survives a CI regression harness.

Not free-of-charge for commercial use at scale. AGPL-3.0 means your SaaS product can use it freely, but if you want to embed KCode in a proprietary offering without publishing the modifications, you need a commercial license ([email protected]).

Try the audit on your repo

Astrolexis — Kulvex Code