AI build velocity.
Production-grade code review.

NextStack orchestrates AI builders, gates their output with multi-model review, and ships code that meets the standard of expert human review. The model-agnostic quality layer for AI-generated code.

"Because the AI that wrote the code shouldn't be the only one reviewing it."

$ npm i -g nextstack click to copy
2,457
Tests
40+
CLI Commands
~60%
Cost Savings
73%
Juice Shop Detection
600
Benchmark Evaluations
4
Models Benchmarked
Model Routing

We benchmarked 4 frontier models across 6 review methods. The result: different models catch different things. ns review routes each method to the best model for the job.

No competitor publishes head-to-head model comparison data. We do. Our routing decisions are backed by 600 controlled evaluations, not assumptions.

Review Method → Best Model
Security
Gemini F1: 0.90
Contracts
GPT F1: 0.76
Correctness
Ensemble consensus
Performance
Ensemble consensus
Readability
Ensemble consensus
Architecture
Ensemble consensus
Security: Gemini +10.3% over runner-up  |  Contracts: GPT +11.4% over runner-up
Every angle covered

Each review method targets a specific class of defects. Model routing sends each method to the model that's empirically best at finding those defects.

Correctness
Functional bugs, logic errors, edge cases, off-by-one mistakes, null handling.
Ensemble consensus
Security
OWASP Top 10, CWE patterns, framework-aware vulnerabilities, injection vectors.
Routed to Gemini — F1: 0.90
Contracts
Data shape mismatches across boundaries, API contract violations, type inconsistencies.
Routed to GPT — F1: 0.76
Performance
N+1 queries, memory leaks, blocking I/O, unnecessary allocations, hot path issues.
Ensemble consensus
Readability
Naming quality, cyclomatic complexity, documentation gaps, cognitive load.
Ensemble consensus
Architecture
SOLID principles, coupling analysis, design pattern violations, dependency direction.
Ensemble consensus
Fix-then-grade, not suggest-then-ignore

Default on your first review — see the full pipeline in action. Configurable after. Code goes through three gates. Only clean code ships.

Gate 1 — Static
Lint + Tests + Contracts
Automated checks that run instantly. Catches the obvious stuff before burning API tokens.
Free — always
Gate 2 — AI Review
Multi-Model Analysis
Each review method routed to its best model. Security to Gemini. Contracts to GPT. Everything else via ensemble consensus.
Model-routed
Gate 3 — Fix & Re-review
Automated Fix Cycle
Findings get fixed automatically, then re-reviewed by a different model until clean. No human round-trips.
Fix-then-grade
Not a PR bot — a quality pipeline

Same PR surface, different depth. CodeRabbit comments once with one model's opinion. ns review uses different models for different review types, then actually fixes the code and re-reviews until clean.

Typical PR Bots ns review
Models Single model Multi-model with empirical routing
Output Suggestions / comments Actual fixes via fix-then-grade
Review types Generic "review this PR" 6 specialized methods, each optimized
Adaptability Static prompts Continuously adapts as models evolve
Benchmark data None published 600 evaluations, 4 models, 6 methods
Fix loop No Fix → re-review → repeat until clean
Start free. Scale when you're ready.

Gate 1 is always free. Multi-model review costs what the API calls cost — no margin stacking.

Free
$0
forever
  • Gate 1: lint + tests + contracts
  • Unlimited reviews
  • CLI access
  • Open source core
Team
$49
per month
  • 20 reviews included
  • Additional reviews at $3/each
  • CI/CD integration
  • Shared review strategies
  • Team dashboard
Open Core

CLI + Gate 1 are open source. Multi-model review + fix-then-grade require an API key.

github.com/ethanholien/nextstack →

Ship code you'd sign off on.

One command. Multi-model review. Automatic fixes. Zero config.

Get Started →
$ npm i -g nextstack click to copy