Founder of Goodspeed
Should you hire a Codex agency or build the capability in-house? It is one of the sharper questions facing any business that wants to ship software with AI coding agents, and the honest answer is that it depends on your situation more than on any universal rule. Both routes can work brilliantly. Both can also waste a great deal of time and money when chosen for the wrong reasons.
We are an AI engineering team that ships production software with agents like Codex and Claude Code, so we have an obvious interest here. That said, we regularly tell companies that in-house is the right move for them, because pretending otherwise would just lead to a bad fit and an unhappy client. The goal of this piece is to give you a clear framework, not a sales pitch.
Here is how to think it through honestly, including when each option genuinely wins.
What you are really choosing between
The choice is not simply agency versus employee. It is between renting a ready-made engineering capability and building your own from scratch. An agency gives you an assembled team with existing practices, tooling, and experience shipping agent-built software. In-house means you recruit, train, equip, and manage that capability yourself, and own it permanently once it exists.
Framing it this way clarifies the real trade-off. You are weighing speed and lower commitment against control and long-term ownership. Neither is inherently better. The right answer depends on how central this software is to your business, how long you will need the capability, and how much appetite you have for building and managing a technical team. Keep that framing in mind as you weigh everything that follows.
The case for an agency: speed to shipped software
The clearest agency advantage is that you can start almost immediately. A capable team is already formed, already fluent with Codex and the surrounding engineering discipline, and already carrying the scar tissue of shipping real software with agents. You skip the months of hiring, onboarding, and figuring out a workflow, and go straight to building the thing you actually need.
For most businesses, that time difference is the whole point. If you need working software in weeks rather than quarters, building a team first is a detour you cannot afford. An agency also absorbs the risk of the capability itself. If an approach does not work, that is their problem to solve, not a hiring mistake you are stuck with. You are buying a result, not assembling the means to produce one.
The case for an agency: breadth without headcount
Good software needs more than one skill. It needs engineering, but also design, security, infrastructure, and ongoing maintenance. An agency brings all of those under one roof for the length of the project, so you get a full team's worth of capability without hiring a full team. For most companies, assembling that breadth in-house is slow and expensive.
This matters especially for agent-built software, where the engineering fluency with tools like Codex is only one ingredient. You still need people who can shape a product, secure it, and keep it running. An agency that does this regularly has all of that in place. Recreating it internally means multiple hires across disciplines, most of whom you may not need full-time once the initial build is done.
The case for in-house: control and continuity
The strongest argument for building in-house is ownership of the capability itself, not just the code. An internal team lives with the software every day, accumulates deep knowledge of your business, and is always available to change things quickly. For software that sits at the centre of how you operate and will keep evolving for years, that continuity is genuinely valuable.
In-house also means the knowledge stays with you. Every problem solved and every decision made compounds inside your organisation rather than walking out the door when a project ends. If the software is a core, permanent part of what you do, and you expect a steady stream of work on it indefinitely, owning the team that builds it can be the right long-term call despite the cost and effort of getting there.
The case for in-house: deep domain immersion
An internal team is immersed in your business in a way an agency rarely matches. They absorb the context, the politics, the history, and the unwritten rules over time, and that depth can make them better at building software that fits your organisation precisely. For businesses whose domain is unusually complex or specific, that accumulated understanding is hard to replicate from outside.
The caveat is that this immersion takes time to build and only pays off if the work is continuous. A team that deeply understands your business but only builds something occasionally is an expensive way to keep that knowledge on the shelf. The domain advantage is real, but it is strongest when paired with a steady, ongoing need for software, not a single project that ends.
The real cost comparison
On paper, in-house can look cheaper per unit of work once the team exists, but that ignores the cost of getting there and keeping it running. Recruitment, salaries, tooling, management, and the productivity lost while a new team finds its feet all add up, and they are ongoing whether or not there is enough work to justify them. An idle capable team is one of the most expensive things a business can carry.
An agency converts that into a variable cost tied to actual work. You pay for output when you need it and stop when you do not. For steady, heavy, long-term demand, the fixed cost of in-house can eventually win. For uneven or finite demand, the flexibility of an agency almost always does. The honest comparison is not hourly rates. It is total cost across the real shape of your demand.
Risk and where it sits
The two routes place risk in different places. With an agency, the risk of the capability sits with them. If a hire does not work out or an approach fails, that is theirs to fix, and you can change agencies far more easily than you can restructure a team. Your main risk is choosing a weak agency, which good diligence largely mitigates.
In-house, you carry the risk directly. A bad hire is slow and painful to correct, key-person dependency is real, and if the workload dries up you still carry the cost. You also take on the risk of building the practices from scratch in a fast-moving field, where an experienced agency has already made and learned from the mistakes you are about to make. Where you want the risk to live is a genuine part of this decision.
A hybrid that often works best
This is rarely a binary. A common and effective pattern is to bring in an agency to build the first version and establish the engineering practices, then transfer knowledge to a small internal team who maintain and evolve it over time. You get speed and experience at the start, and ownership and continuity for the long run.
For this to work, ownership and handover have to be clean from the beginning, which is exactly why we press so hard on those points. You want full access to the code and infrastructure and a deliberate transfer of knowledge, not a dependency on the agency's private tooling. Done well, the hybrid gives you the best of both. The agency de-risks the hard early phase, and your internal team inherits something they can genuinely own.
When an agency clearly wins
Choose an agency when you need working software quickly, when the demand is finite or uneven rather than a permanent stream, and when you do not want to take on the cost and management of building a technical team. It is also the better choice when you lack the internal expertise to hire and direct agent-native engineers well, because getting that hiring wrong is expensive and slow to fix.
An agency is similarly the right call when you want the breadth of a full team, design, security, infrastructure, and engineering, for a defined period without carrying all of it permanently. In short, when speed, flexibility, and access to ready-made capability matter more than owning the team, an agency is usually the stronger route, and the one that gets you to a result fastest.
When in-house clearly wins
Build in-house when the software is core to your business, will evolve continuously for years, and generates enough steady work to keep a team genuinely busy. In that situation the continuity, deep domain knowledge, and accumulated ownership justify the cost and effort, and the fixed cost is spread across enough work to make sense.
It also wins when your competitive edge depends on keeping the capability and its knowledge entirely inside the business, or when your domain is so specialised that only deep, permanent immersion produces good software. If you have both the appetite to build and manage a team and a durable, heavy need for their work, in-house is the route that compounds value over the long term rather than renting it.
How to make the call
Work through a few honest questions. How central is this software to the business, and how long will you need to keep changing it. Is the demand steady and heavy, or finite and uneven. Do you have the appetite and skill to hire, direct, and manage agent-native engineers. And how quickly do you need results. Your answers will usually point clearly one way.
If they point in different directions, the hybrid path is often the resolution. Whatever you choose, decide for reasons grounded in your actual situation rather than a general belief that owning a team is always better or that outsourcing is always cheaper. Both beliefs are wrong as often as they are right. The correct answer is the one that fits the real shape of your need, your timeline, and your appetite for building.
Conclusion
Codex agency versus in-house is a genuine trade-off, not a question with one right answer. An agency wins on speed, breadth, and flexibility, and shifts the risk of the capability onto someone else. In-house wins on control, continuity, and deep domain immersion when the software is core and the demand is durable. Many businesses get the best result from a hybrid, using an agency to build and de-risk the first version and an internal team to own it thereafter.
Decide based on how central the software is, how long you will need it, and how steady the work will be. Those answers, not a general preference, should settle it.
If you want a team that ships production software with AI coding agents, see our AI work, or book a free call with our AI engineering team.
Written By
Founder of Goodspeed