xIn-house, freelancer or agency? How to staff a Python web project
Hiring, contracting and outsourcing each suit different stages of a product. Here is how they compare on cost, speed and risk in the UK, including what a senior in-house Python developer really costs in the first year.
- In-house is cheapest over several years for a core product, but slowest to start.
- Freelancers are flexible for well-defined work, but you carry the management and the risk.
- Agencies cost more per day and start fastest, with a whole team and cover built in.
- Many teams combine them: an agency builds version one, then hands over to in-house hires.
The three options at a glance
| In-house | Freelancer | Agency | |
|---|---|---|---|
| Time to start | Typically 2–4 months | 1–4 weeks | 1–3 weeks |
| Cost shape | Salary plus overheads, ongoing | Day rate, flexible | Day or monthly rate, flexible |
| Management | Yours | Yours | Shared |
| Cover for holidays and illness | Needs a team | None | Built in |
| Best for | Long-lived core products | Defined, short tasks | New builds, upgrades, spikes |
Hiring in-house: the real cost
The salary is only part of the cost. For a senior Python developer on £80,000, a realistic first year in 2026 looks like this:
| Item | Approximate cost |
|---|---|
| Salary | £80,000 |
| Employer National Insurance (15% above £5,000) | £11,250 |
| Employer pension (3% of qualifying earnings, the legal minimum) | £1,320 |
| Recruitment agency fee (often 15–25% of salary) | £16,000 |
| Laptop, software and other overheads | £3,000 |
| First-year total | about £111,500 |
After the first year, without the recruitment fee, the same developer costs around £95,000 a year, or roughly £8,000 a month. Over several years that is good value for a product at the centre of your business.
The hidden cost is time. Advertising, interviewing and notice periods (often one to three months for senior people) mean a new hire commonly starts two to four months after you decide to hire. A single developer also has no cover for holidays or illness, so most products need at least two.
Salary levels vary by region and change quickly, so check current salary surveys for your area. The employer National Insurance rate and threshold shown apply from April 2025.
Freelancers and contractors
A good freelancer can start within weeks and suits well-defined work: a specific integration, a performance fix or extra capacity before a launch. Senior Python contractors in the UK commonly charge somewhere around £450–£700 a day, depending on experience and location.
Two things to plan for. First, you manage the work: priorities, reviews, testing and deployment are on your side. Second, IR35. Since April 2021, medium and large private-sector clients must decide whether each contractor is inside or outside IR35 and issue a status determination. Getting it wrong can mean backdated tax and National Insurance. Small businesses leave that decision to the contractor.
The biggest risk is concentration. If one freelancer holds all the knowledge of your system and moves on, you may be paying the next person to rediscover it.
Agencies
An agency costs more per day than a single freelancer, but you buy a team: engineers with different strengths, someone to run delivery, code review, testing, and cover when people are away. Good agencies also bring patterns from many similar projects, which is where most of the speed comes from.
Agencies work best when the work has a clear outcome and a start and end: a new product, a first version, a Django upgrade or a migration. For ongoing capacity inside your own team, many agencies also offer developers on a monthly basis.
Combining the options
The choice is rarely all or nothing. Three patterns we see work well:
- Agency first, then in-house. An agency builds and launches version one while you hire. Your new developers join a working product with tests and documentation, and the agency hands over.
- Staff augmentation. Senior engineers join your existing team on a rolling monthly basis to cover a gap or a deadline, working in your repository and your rituals.
- White-label. Digital agencies without Python expertise bring in a specialist team that works under their brand, with their clients.
How to decide
- Is this software at the core of your business for years to come? Plan to build an in-house team, and consider an agency to get there faster.
- Is the work well-defined and short, with someone technical on your side to manage it? A freelancer may be the most cost-effective choice.
- Do you need to start this month, with a whole team and no hiring risk? An agency or engineers on a monthly basis.
- Is nobody on your side technical? Choose an agency that will own delivery, not just supply people.
Need senior Django or FastAPI engineers without a four-month hiring process? Our developers for hire join your team within a week, from £7.5k–£10k per engineer per month on a rolling basis. If you are still shortlisting, read 12 questions to ask a Django agency.
Questions
Is it cheaper to hire a developer or use an agency?
Over several years, an in-house developer is usually cheaper per month. For a project of a few months, an agency is often cheaper overall once recruitment fees, hiring time and management are counted.
How long does it take to hire a senior Python developer in the UK?
Commonly two to four months from starting the search to their first day, because senior candidates usually have notice periods of one to three months.
Do I need to worry about IR35 when using an agency?
When you contract an agency to deliver a project or provide its own employed engineers, the off-payroll rules generally do not apply in the way they do for individual contractors working through their own limited companies. Take advice for your specific arrangement.