PRowl

The multi-agent PR reviewer that never misses a bug.

Open-source, self-hostable GitHub Action. Works with any LLM provider.

How It Works

flowchart TD
    subgraph GitHub["GitHub CI/CD"]
        PR([Pull Request Opened / Updated])
        GH[GitHub API\nFetch PR Diff]
        CM[Post Inline Review\nComments with Fix Suggestions]
    end

    subgraph Action["AI Code Reviewer Action"]
        TOON[TOON Encoder\nCompact token-efficient diff]

        subgraph Orchestrator["Orchestrator Pipeline"]
            A1["Agent 1 — Reviewer\n🔍 cheap / fast model\nDetects BUG · SECURITY\nPERF · BEST_PRACTICE"]
            CHK{Issues found?}
            A2["Agent 2 — Explainer + Fixer\n🧠 smarter model\nExplanation + fixed code\nper issue · runs in parallel"]
        end
    end

    PR --> GH --> TOON --> A1 --> CHK
    CHK -- No issues --> DONE([Done — zero fixer cost])
    CHK -- Issues found --> A2 --> CM

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1. Triggers on PR open/update
2. Fetches code diff from GitHub
3. Encodes all changed chunks into token-efficient TOON format
4. Agent 1 (Reviewer) — sends the full TOON diff to a cheap/fast model; detects BUG, SECURITY, PERFORMANCE, BEST_PRACTICE issues and returns a typed list
5. If no issues are found → pipeline stops; Agent 2 is never called (zero extra cost)
6. Agent 2 (Explainer+Fixer) — for each flagged chunk (not the full diff), generates an explanation and corrected code in a single LLM call; all issues are processed in parallel
7. Posts inline PR comments with: issue type label, concise explanation, and a GitHub suggestion block with the fixed code

Features

• 🔓 Open Source - Self-hostable, no vendor lock-in
• 🔑 BYOK - Bring Your Own API Key
• 🌐 Multi-Provider - OpenAI, Groq, Mistral, DeepSeek, Gemini, and more
• ⚡ Token-Efficient - 50-70% cost reduction with TOON encoding
• 🤖 2-Agent Pipeline - Cheap model detects issues; smarter model explains and fixes them
• 💰 Zero Downstream Cost - Fixer agent is skipped entirely when no issues are found

Supported Providers

Works with any OpenAI-compatible API:

Provider	Free Tier?	Base URL
OpenAI	No	(default)
Groq	✅ Yes	https://api.groq.com/openai/v1
DeepSeek	✅ Yes	https://api.deepseek.com/v1
Mistral	✅ Yes	https://api.mistral.ai/v1
Together AI	✅ Yes	https://api.together.xyz/v1
Fireworks	✅ Yes	https://api.fireworks.ai/inference/v1
OpenRouter	No	https://openrouter.ai/api/v1
Google Gemini	✅ Yes	https://generativelanguage.googleapis.com/v1beta/openai

Quick Start

1. Get an API Key

Pick any provider above. For free options, try Groq or DeepSeek.

2. Add Secret to Your Repo

Go to: Settings → Secrets → Actions → New repository secret

• Name: LLM_API_KEY
• Value: Your API key

3. Create Workflow

Create .github/workflows/ai-review.yml:

name: AI Code Review

on:
  pull_request:
    types: [opened, synchronize]

permissions:
  contents: read
  pull-requests: write

jobs:
  review:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - uses: tusharshah21/ai-code-reviewer@main
        with:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          LLM_API_KEY: ${{ secrets.LLM_API_KEY }}
          LLM_MODEL: "gpt-4o"

# Optional: Discord + Slack notifications

Add any of these optional secrets if you want commit-trigger and review-result notifications in chat:

- `DISCORD_WEBHOOK_URL` for Discord channel notifications
- `SLACK_BOT_TOKEN` + `SLACK_CHANNEL_ID` for threaded Slack notifications (recommended)
- `SLACK_WEBHOOK_URL` for basic Slack notifications (fallback, non-threaded)

Example:

```yaml
      - uses: tusharshah21/ai-code-reviewer@main
        with:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          LLM_API_KEY: ${{ secrets.LLM_API_KEY }}
          LLM_MODEL: "gpt-4o"
          DISCORD_WEBHOOK_URL: ${{ secrets.DISCORD_WEBHOOK_URL }}
          SLACK_BOT_TOKEN: ${{ secrets.SLACK_BOT_TOKEN }}
          SLACK_CHANNEL_ID: ${{ secrets.SLACK_CHANNEL_ID }}

That's it! PRs will now get AI reviews with explanation and fix suggestions.

#### Optional: Use separate models for detection vs. fixing

```yaml
      - uses: tusharshah21/ai-code-reviewer@main
        with:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          LLM_API_KEY: ${{ secrets.LLM_API_KEY }}
          LLM_REVIEWER_MODEL: "gpt-4o-mini"   # cheap & fast for triage
          LLM_FIXER_MODEL: "gpt-4o"           # smarter for explanations & fixes

---

Provider Examples

OpenAI (default)

LLM_API_KEY: ${{ secrets.OPENAI_API_KEY }}
LLM_MODEL: "gpt-4o"

Groq (FREE & Fast)

LLM_API_KEY: ${{ secrets.GROQ_API_KEY }}
LLM_MODEL: "llama-3.3-70b-versatile"
LLM_BASE_URL: "https://api.groq.com/openai/v1"

DeepSeek (FREE & Cheap)

LLM_API_KEY: ${{ secrets.DEEPSEEK_API_KEY }}
LLM_MODEL: "deepseek-chat"
LLM_BASE_URL: "https://api.deepseek.com/v1"

Mistral AI

LLM_API_KEY: ${{ secrets.MISTRAL_API_KEY }}
LLM_MODEL: "mistral-large-latest"
LLM_BASE_URL: "https://api.mistral.ai/v1"

Google Gemini

LLM_API_KEY: ${{ secrets.GOOGLE_API_KEY }}
LLM_MODEL: "gemini-1.5-flash"
LLM_BASE_URL: "https://generativelanguage.googleapis.com/v1beta/openai"

Together AI

LLM_API_KEY: ${{ secrets.TOGETHER_API_KEY }}
LLM_MODEL: "meta-llama/Llama-3.3-70B-Instruct-Turbo"
LLM_BASE_URL: "https://api.together.xyz/v1"

OpenRouter (100+ models)

LLM_API_KEY: ${{ secrets.OPENROUTER_API_KEY }}
LLM_MODEL: "anthropic/claude-3.5-sonnet"
LLM_BASE_URL: "https://openrouter.ai/api/v1"

---

Configuration

Input	Required	Default	Description
GITHUB_TOKEN	Yes	-	Auto-provided by GitHub
LLM_API_KEY	Yes	-	Your provider's API key
LLM_MODEL	No	gpt-4o	Model used by both agents. If you only set this, both agents run on the same model. Set LLM_REVIEWER_MODEL / LLM_FIXER_MODEL to split them.
LLM_BASE_URL	No	OpenAI	Provider's API endpoint
LLM_REVIEWER_MODEL	No	LLM_MODEL	Fast/cheap model for issue detection (Agent 1). Overrides LLM_MODEL for Agent 1 only.
LLM_FIXER_MODEL	No	LLM_MODEL	Smarter model for explanation and fix generation (Agent 2). Overrides LLM_MODEL for Agent 2 only.
exclude	No	-	Files to skip (glob patterns)
DISCORD_WEBHOOK_URL	No	-	Posts a start message (commit/PR context) and a reply with reviewer results to Discord.
SLACK_BOT_TOKEN	No	-	Slack bot token (xoxb-...) used for threaded messages via chat.postMessage.
SLACK_CHANNEL_ID	No	-	Slack channel ID for bot-thread notifications. Used with SLACK_BOT_TOKEN.
SLACK_WEBHOOK_URL	No	-	Slack incoming webhook fallback (non-threaded) when bot token/channel are not provided.

---

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Cost Comparison

TOON encoding saves 50-70% tokens. Example for reviewing 1000 lines:

Provider	Model	Cost/Review
Groq	Llama 3.3 70B	FREE
DeepSeek	DeepSeek Chat	~$0.001
OpenAI	GPT-4o	~$0.02
OpenAI	GPT-4o-mini	~$0.002

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Presentation

View the PRowl pitch deck →

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License

MIT - Free and open source #PRowl