The decision between hiring a developer and hiring an agency or consultancy comes down to three factors: whether there's enough steady work to fill a full-time role, what cost shape the company can absorb, and which continuity risk it can tolerate. The honest answer changes as a company grows, so the right choice at 10 employees isn't necessarily the right choice at 100.
The decision at a glance
| In-house hire | Agency or consultancy | |
|---|---|---|
| Volume of work | Needs a steady, full-time backlog | Fits intermittent or project-based work |
| Cost shape | Salary, benefits, and management overhead, year-round | Paid for the work delivered, scoped by project |
| Continuity risk | One person leaving stalls the work | Vendor relationship persists past any one person |
When in-house wins
In-house hiring makes sense once there's genuinely enough work to keep someone busy full-time, indefinitely. If the backlog of features, fixes, and maintenance would fill 40 hours a week for the next year and beyond, a full-time hire is usually cheaper than paying an outside rate for the same hours. In-house developers also build institutional knowledge that compounds: they understand the business context behind decisions, not just the code.
The catch is that this only holds if the work is actually steady. A company that hires a developer for a six-month push and then has nothing for them to do for the following six months hasn't saved money. It has paid full-time cost for part-time output.
When an agency wins
An agency or consultancy fits when the work is project-shaped rather than ongoing: a new product build, a platform migration, a specific integration. You get a team that has already solved similar problems, without carrying them on payroll once the project ends. This also works well when a company needs a skill it will only need once, like a data migration or a security audit, where hiring a full-time specialist for a one-time need doesn't make sense.
The tradeoff is that an agency's institutional knowledge of your business starts lower than an employee's and has to be rebuilt on future engagements unless the relationship continues.
The continuity risk runs both directions
The risk with an in-house hire is concentration: if the one developer who understands the system leaves, takes vacation, or gets sick, progress stops until someone else gets up to speed. That knowledge often isn't written down anywhere.
The risk with an agency is the reverse: if the vendor relationship ends, whether by choice or because the agency changes focus, you need someone who can pick up documented, maintainable work rather than a black box only the original team understood. The way to manage this isn't to avoid agencies. It's to require documentation and clean handoff as part of the engagement, so the work outlives any single relationship.
Making the call
Volume of work points to in-house or agency. Cost shape and continuity risk decide which one is worth the tradeoff. Many companies end up with both: an in-house developer handling day-to-day work, with a consultancy brought in for specific builds or specialized problems the in-house team doesn't have bandwidth or expertise for. If leadership, not headcount, turns out to be the actual gap, that's a related but different question, covered in Hiring Developers vs. Hiring Leadership.
Datarex builds under a fixed-scope discovery first, so you see the plan and the number before committing to the build. See how that works for web development, or check the pricing page for how discovery and build phases are structured.