When a purchased product needs a feature that isn't in the base spec, our engineers build it directly into your codebase — no bolted-on workarounds.
$6,000
Scoped to your specific engagement
A launch-ready product gets you 90% of the way, but the last 10% — the feature that makes your business different — usually isn't in the base listing. Custom Development is our engineering team extending your purchased codebase with exactly that, without breaking upgrade paths or introducing technical debt.
What to expect — typical ranges, not guarantees
2–6 wks
Typical feature delivery
100%
Regression-tested before handoff
0
New technical debt, by design
Fixed
Price agreed before work starts
Turn your feature request into a written technical specification with acceptance criteria.
Implement directly in your codebase, following the product's existing architecture and conventions.
Full regression testing to confirm the new feature doesn't break existing functionality.
Deliver the merged code plus documentation for your team to maintain going forward.
Senior Full-stack Engineer
Implements following the product's existing architecture
Solutions Architect
Writes the technical spec and reviews design decisions
QA Engineer
Runs full regression testing before handoff
| Model | Scope | Timeline | Price |
|---|---|---|---|
| Scoped sprint | Fixed price per single feature | 2–6 weeks | $6,000+ |
| Dedicated pod | Multiple features, ongoing | Monthly | See Product Engineering |
Stack18's services practice is new — the scenarios below illustrate how an engagement like this typically plays out, not verified past-client results.
Illustrative scenario
New operational modules
Field service software buyer
Added route optimization, custom reporting, and a partner API layer that weren't in the base product.
Illustrative scenario
Jurisdiction-specific tax engine
Fintech ledger buyer
Built a jurisdiction-specific tax calculation module directly into the purchased ledger core.
Engagement
Scoped sprint
Fixed-price per feature
Starting at
$6,000
Single feature scope
Timeline
2–6 weeks
Depending on complexity
Final pricing depends on scope confirmed during a consultation — the figures above reflect typical starting points, not a fixed quote.
We build following the product's existing conventions specifically to minimize this risk, and document every change for future maintainers.
Yes, ongoing maintenance is available through our Product Engineering retainer service.
No — custom code is developed and documented separately, and clearly delineated from the base product for support purposes.
Yes, the Spec phase exists specifically to turn a rough idea into a written specification with acceptance criteria before any code is written.
We flag scope changes as soon as they're identified and re-quote before continuing, so there are no surprise invoices.
Yes, all custom code, specs, and test artifacts are assigned to you as part of every engagement.
Book a free consultation — no commitment, just a clear plan and a real quote.
Book a free consultation