Overall Verdict
BUY
Build hours
76h
Build cost/year
$13,800.00
Buy cost/year
$840.00
AI Product Economics
Build vs Buy Decision Engine
Compare the true cost of building infrastructure yourself versus buying managed services. Build/buy verdict per component with break-even analysis.
Auth
BUYBuild (one-time)$3,000.00
Maintain (annual)$1,800.00
Buy (annual)$300.00
Buying Auth at $25/mo costs $300/year but saves 40h upfront + 2h/mo of your time ($4800/year equivalent).
Database
BUYBuild (one-time)$1,500.00
Maintain (annual)$3,600.00
Buy (annual)$300.00
Buying Database at $25/mo costs $300/year but saves 20h upfront + 4h/mo of your time ($5100/year equivalent).
Hosting
BUYBuild (one-time)$1,200.00
Maintain (annual)$2,700.00
Buy (annual)$240.00
Buying Hosting at $20/mo costs $240/year but saves 16h upfront + 3h/mo of your time ($3900/year equivalent).
Key insight
Building everything yourself costs $13800/year in your time. Buying saves 9 hours/month for $70/month. At $75/hour, buying frees up time worth more than the subscription cost.
How to use it
- Set your hourly value — this is what your time is worth as a solo founder. Use your effective hourly rate from consulting or the opportunity cost of not building product.
- Toggle which infrastructure components to evaluate: Auth, Database, Hosting, Payments, Email, Monitoring, Analytics. Enable only the ones relevant to your build.
- For each enabled component, enter hours to build from scratch, hours per month to maintain, and the managed service cost per month.
- Read the per-component BUILD or BUY verdict with break-even months. Some components may be worth building (low maintenance) while others clearly favor buying (high maintenance, low cost).
- Check the overall verdict and total annual cost comparison. The key insight shows the total hours per month your build choice requires — if that exceeds your available maintenance bandwidth, buy.
AI Integrations
Contract, discovery endpoints, and developer notes for agent use.
Always available for agents
AI Integrations
Contract, discovery endpoints, and developer notes for agent use.
Tool contract JSON
https://aibizhub.io/contracts/build-vs-buy-decision-engine.jsonStable input and output contract for this exact tool.
Human review
People can use the browser page to sense-check outputs and charts, but agents should still execute against the contract and discovery endpoints.
- /agent-tools.json - machine-readable tool index.
- /llms.txt - human-readable model discovery guide.
- /.well-known/webmcp.json - WebMCP capabilities manifest.
- /.well-known/ai-plugin.json - plugin-style discovery manifest.
{
"tool": "build_vs_buy_decision_engine",
"hourly_value": 75,
"components": [
{
"name": "auth",
"enabled": true,
"time_to_build_hours": 40,
"maintenance_hours_per_month": 2,
"managed_service_cost": 25
},
{
"name": "database",
"enabled": true,
"time_to_build_hours": 20,
"maintenance_hours_per_month": 4,
"managed_service_cost": 25
},
{
"name": "hosting",
"enabled": true,
"time_to_build_hours": 16,
"maintenance_hours_per_month": 3,
"managed_service_cost": 20
}
]
} Expand developer notes
Agent playbook
- Resolve Build vs Buy Decision Engine from /agent-tools.json and open its contract before execution.
- Validate inputs against the contract schema instead of scraping labels from the page UI.
- Open the browser page only when a person wants to review charts, assumptions, or related tools.
Agent FAQ
Should ChatGPT, Claude, or another agent click through the UI?
No. Start with /agent-tools.json, then follow the tool's contract URL. The page UI is for human review, not parameter discovery.
When do tools show Quick and Advanced?
Every tool opens in Quick Start first. Advanced Controls keeps the same scenario, reveals more assumptions or diagnostics, and every tool keeps AI integrations inline below the instructions.
When should an agent still open the browser page?
Open it when a human wants to sense-check the output, review the chart, or keep exploring related tools after the calculation finishes.
Questions people usually ask
How does the build vs buy verdict work?
For each component, the tool compares annual build cost (build hours x hourly rate + maintenance hours x hourly rate x 12) against annual buy cost (managed service x 12). Whichever is lower gets the verdict.
What is the break-even months metric?
Break-even months shows how long until the upfront build investment pays for itself through savings vs the managed service monthly cost. If maintenance cost exceeds the managed service cost, there is no break-even.
What hourly value should I use?
Use your effective hourly rate or opportunity cost. If you could bill $150/hour as a consultant, that is your hourly value — even if you are not billing during build time. Time spent building infrastructure is time not spent on product or customers.
Should I build everything or buy everything?
Almost never all one way. Low-maintenance, well-documented systems (like auth with NextAuth) can be worth building. High-maintenance, commoditized services (like email delivery) are almost always worth buying.
Is this tool free and private?
Yes. All calculations run in your browser. No data is sent anywhere. No signup required.
Related Resources
Learn the decision before you act
Every link here is tied directly to Build vs Buy Decision Engine. Use the explanation, formula, examples, and benchmarks to pressure-test the calculator output from first principles.
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