Startup Runway Simulator

Will you ship your MVP before running out of money? Find out instantly.

Access: /tools/clients/runway

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Overview

The Runway Simulator is an interactive financial modeling tool for startup founders. It visualizes how your decisions about budget, team composition, and technology stack affect your ability to ship before bankruptcy.

Key features:

• Real-time interactive simulation
• Visual cash burn vs progress chart
• Smart scenario comparisons
• CTO-style insights
• No AI required - pure mathematics

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How It Works

Input Parameters

1. Starting Budget

• Range: £10,000 - £500,000
• Step: £5,000
• Affects: Total runway available

2. Tech Stack (3 options)

3. Team Composition (4 options)

4. Revenue Projection (optional)

• Toggle: Enable/disable post-MVP revenue
• Range: £1,000 - £50,000/month
• Starts: Month after MVP completion

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The Simulation

Core Calculations

Monthly Burn Rate:

burn = teamCost + infraCost

Development Velocity:

progress = baseVelocity × stackMultiplier

Month-by-Month Loop:

1. Deduct burn from cash
2. Add velocity to progress
3. Check for MVP completion (100%)
4. Add revenue if MVP complete
5. Check for bankruptcy (cash ≤ 0)

Outcomes

Success (Green)

• MVP completed before running out of money
• Shows final cash remaining
• Celebrates with confetti

Bankruptcy (Red)

• Cash depleted before MVP completion
• Shows what percentage was completed
• Offers "Fix It" suggestions

Scalability Limit (Amber)

• No-code stack hits 80% ceiling
• Can't complete MVP without code rewrite
• Suggests developer hiring

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The Chart

Interactive dual-axis visualization:

Left Axis (Green Area): Cash remaining over time Right Axis (Blue Line): MVP progress percentage Red Dashed Line: £0 bankruptcy threshold Blue Dashed Line: 100% MVP completion

"Gap of Death"

Red shaded zone between:

• When you went bankrupt
• When MVP would have completed

This visualizes exactly how close you were to success.

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Example Scenarios

Scenario 1: Lean Success

Budget: £50,000
Stack: Monolith
Team: Senior Dev
Revenue: Disabled

Result: MVP ships in Month 9 with £22,000 remaining

Scenario 2: Overhiring Failure

Budget: £100,000
Stack: Microservices
Team: Dream Team
Revenue: Disabled

Result: Bankrupt in Month 5 with MVP at 65%

Scenario 3: No-Code Trap

Budget: £30,000
Stack: No-Code/Bubble
Team: Junior Dev
Revenue: Disabled

Result: Stuck at 80% - scalability limit reached

Scenario 4: Revenue Sustainability

Budget: £75,000
Stack: Monolith
Team: Senior Dev
Revenue: £15,000/mo after MVP

Result: MVP ships Month 8, cash stabilizes at £20k+

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CTO Insights

The simulator provides context-aware advice:

On Microservices Failure

"Microservices add significant overhead in early stages. You're paying for infrastructure complexity before you've validated your product. 90% of startups should start with a monolith."

On No-Code Limits

"No-code tools are great for validation, but they have hard limits. When you hit that wall, you need a migration strategy. Consider hiring a developer for the next phase."

On Dream Team Risk

"Great for scaling, but dangerous for pre-PMF startups. Communication overhead increases quadratically. A single senior dev often ships faster than a large team."

On Successful Monolith

"A monolith is the right choice for most startups at this stage. You can always extract microservices later when you have product-market fit and revenue to justify the complexity."

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Survival Insights

When you fail with suboptimal choices, the simulator runs shadow scenarios to show alternatives:

Microservices → Monolith:

"Switching to Monolith would have saved you £4,500 in infra costs and launched the product 3 months earlier."

Dream Team → Senior Dev:

"A smaller team reduces burn rate significantly. A single Senior Dev would have kept you alive and shipped the MVP with £15,000 remaining."

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"Fix It" Button

One-click optimization that:

1. Switches Microservices → Monolith
2. Switches Dream Team → Senior Dev
3. Shows immediate impact of changes

Helps founders understand the value of lean decisions.

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Technical Details

Formulas

Progress per month:

velocity = baseVelocity × techMultiplier
progress = min(progress + velocity, scalabilityLimit)

Cash per month:

cash = cash - teamCost - infraCost
if (mvpComplete && revenueEnabled) cash += revenue

Bankruptcy check:

if (cash <= 0 && !mvpComplete) → failure

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Assumptions & Limitations

What's Modeled

• Linear development progress
• Fixed monthly costs
• Binary MVP completion
• Single product focus

What's Not Modeled

• Pivots and scope changes
• Hiring/firing mid-project
• Variable revenue growth
• External funding rounds
• Non-linear progress curves

Reality Check

This is a simplified model for education. Real startups face:

• Unexpected technical challenges
• Market timing
• Team dynamics
• Competition
• Regulatory hurdles

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Key Lessons

1. Monolith First

Most startups should start with a monolith. Extract services only when you have PMF and scale requirements.

2. Small Teams Ship Faster

A single senior developer often outperforms a large team due to communication overhead.

3. Revenue Changes Everything

Even modest post-MVP revenue can extend runway indefinitely and reduce pressure.

4. Lean Infrastructure

£500/mo vs £50/mo compounds over a year into £5,400 of runway.

5. Speed > Perfection

Shipping a working product beats perfect architecture every time.

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Privacy & Security

• 100% client-side - No data sent to servers
• No storage - Nothing persisted
• No tracking - Budget/team choices not logged
• No account required - Use anonymously

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Use Cases

• Founders planning burn rate and hiring
• Investors validating founder's financial planning
• Accelerators educating cohort on runway management
• CTOs explaining tech debt vs speed trade-offs
• Students learning startup economics