Flow Simulator
GitHub Flow vs. trunk-based development side by side
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What is Flow Simulator?
Flow Simulator is an interactive visualization tool that models how software development work flows through three different Git branching strategies: GitHub Flow, Git Flow, and Trunk-Based Development (TBD). Created by Jason Gorman based on 15 years of experience working with teams of all shapes and sizes, the simulator lets users watch pull requests pile up, review interrupts cascade, and merge conflicts grow under different branching strategies side by side.
The tool visually demonstrates the real-world consequences of each branching model by simulating how code moves from idea to production. Users can observe how PRs accumulate under GitHub Flow and Git Flow compared to the streamlined approach of Trunk-Based Development. The simulator includes an AI slop injection feature that adds extra chaos to demonstrate how each strategy handles poor-quality code or chaotic development scenarios.
Flow Simulator is designed for software development teams, engineering managers, DevOps practitioners, and anyone interested in understanding the impact of Git branching strategies on team productivity and code flow. It serves as an educational tool for teams considering switching to trunk-based development or evaluating their current branching strategy, making abstract concepts about CI/CD and continuous delivery tangible through visual simulation.
Flow Simulator pricing
Pricing model: Freemium
The Flow Simulator is completely free to use with no subscription required. It is part of Mainline's offerings where the CI monitor app is also free forever on the GitHub marketplace. No payment or trial is needed to access the flow simulator functionality.
Flow Simulator pros
- Visualizes three branching strategies side by side for direct comparison
- Shows real consequences of PR pile-ups under different workflows
- Demonstrates how merge conflicts accumulate in Git Flow vs TBD
- Illustrates review interrupt cascades visually
- Based on 15 years of practical team experience
- Makes abstract CI/CD concepts tangible through simulation
- AI slop injection feature adds chaos testing capability
- No subscription or payment required - free forever
- Helps teams understand why TBD reduces merge hell
- Shows code flow from idea to production clearly
- Educational tool for branching strategy decisions
- Interactive tabs allow switching between strategies easily
- Demonstrates trunk-based development advantages concretely
- Over 100,000 people have used the simulator
- Helps justify switching to trunk-based development to stakeholders
Flow Simulator cons
- Simplified 'back-of-the-napkin' model may not capture all real complexities
- May have caused controversy among Git Flow proponents
- Does not account for team size variations beyond basic simulation
- AI slop feature might be seen as gimmicky by some users
- No export functionality for simulation results
- Limited customization of simulation parameters
- Does not integrate with actual GitHub repositories
- Single-view presentation may not suit all learning styles
Frequently asked questions about Flow Simulator
What is the Flow Simulator?
Flow Simulator is an interactive visualization tool that models how software development work flows through three different Git branching strategies: GitHub Flow, Git Flow, and Trunk-Based Development. It shows how code moves from idea to production under each strategy side by side, making it easy to see the consequences of different branching approaches.
Who created the Flow Simulator?
The Flow Simulator was created by Jason Gorman, who built it based on 15 years of experience working with teams of all shapes and sizes. He has shared it on platforms like Hacker News and LinkedIn, where it gained over 100,000 users.
What three branching strategies does the simulator compare?
The simulator compares GitHub Flow, Git Flow, and Trunk-Based Development (TBD). Users can watch how pull requests, merge conflicts, and review interrupts behave under each strategy by switching between tabs to see the same team working with different approaches.
Is the Flow Simulator free to use?
Yes, the Flow Simulator is completely free to use with no subscription required. It follows Mainline's philosophy of free tools, similar to their CI monitor app which is free forever on the GitHub marketplace.
What is the AI slop injection feature?
The AI slop injection is a chaos feature that injects poor-quality code into the simulation to demonstrate how each branching strategy handles bad code or chaotic development scenarios. It adds extra stress to see how PRs, conflicts, and reviews behave under difficult conditions.
How does Trunk-Based Development differ from GitHub Flow in the simulator?
In the simulator, Trunk-Based Development shows significantly fewer PR pile-ups, fewer merge conflicts, and less review interrupt cascades compared to GitHub Flow. TBD demonstrates streamlined code flow because developers merge small, frequent updates to the main branch instead of maintaining long-lived feature branches.
What problem does the Flow Simulator help solve?
The Flow Simulator helps teams understand the real consequences of their Git branching strategy choices. It makes visible the hidden costs of Git Flow and GitHub Flow like merge hell, PR accumulation, and review bottlenecks, helping teams justify switching to trunk-based development.
Is the simulation model accurate to real life?
The simulator is described as a 'back-of-the-napkin' model, meaning it's a simplified representation based on practical experience rather than a rigorous mathematical model. While it captures the essential dynamics of each branching strategy, it may not capture all complexities of real development teams.
How many people have used the Flow Simulator?
Over 100,000 people have used the Flow Simulator since its release, according to Jason Gorman's LinkedIn post. The simulator caused some controversy but gained significant traction among development teams.
Can I use the Flow Simulator to convince my team to switch to TBD?
Yes, the Flow Simulator is specifically designed as an educational tool to help teams understand why Trunk-Based Development reduces merge hell and improves code flow. The side-by-side comparison makes it easy to show stakeholders the concrete advantages of TBD over GitHub Flow or Git Flow.