Decision tool
Build vs buy.
A back-of-envelope worksheet for the CIAM build-vs-buy decision. Slide the inputs; the model recomputes a 5-year cumulative comparison and the breakeven year. The defaults bias toward making "build" honestly expensive, most teams underestimate maintenance and compliance costs.
Inputs
3-year build
$884k
3-year buy
$60k
Breakeven
Buy stays cheaper >5y
Cumulative cost over 5 years
| Year | Cumulative build | Cumulative buy | Delta |
|---|---|---|---|
| Year 1 | $578k | $48k | +$530k buy wins |
| Year 2 | $731k | $54k | +$678k buy wins |
| Year 3 | $884k | $60k | +$825k buy wins |
| Year 4 | $1.04M | $66k | +$972k buy wins |
| Year 5 | $1.19M | $72k | +$1.12M buy wins |
Cumulative cost over time
Build Buy
Model assumptions
- Build initial cost = engineers × months × (loaded cost / 12) + $50k for SOC 2 Type 2 initial audit.
- Build annual maintenance = (maintenance % × engineers × loaded cost) + 5% security-incident allowance + $25k SOC 2 annual.
- Buy initial cost = 2 engineer-months for SDK integration and cutover.
- Buy annual cost = vendor monthly × 12. Use the TCO calculator to project this at your MAU and growth.
- Compliance, security incidents, and ongoing feature work are real costs of in-house CIAM that are commonly underestimated. The defaults bias toward making "build" honestly expensive.
For framework, see the build vs buy guide.