ON3 Works recruits engineers for London teams: AI screens to a qualified shortlist in 24 to 48 hours, then a senior engineer interviews every finalist before you see them. Fees are 7% (Agentic, AI-led) or 20% (Atelier, engineer-vetted), no deposit, in GBP, so the Agentic tier often costs less than hiring in-house. In a city where strong engineers are gone within days, that speed plus a real technical vet is the combination London hiring needs.
The hardest, fastest engineering market in Europe
London is the highest-paying tech market in Europe, and the most competitive to hire in. Demand is pulled hardest by AI/ML, data, cloud and DevOps, and payments infrastructure, with the city's trading and fintech firms pushing the salary ceiling higher than anywhere else on the continent. That density is good news for supply and brutal for speed: the strongest engineers field multiple approaches and are off the market within days.
Based on ON3's index of 1.7M+ UK and Spanish technical profiles, a backend engineer in London sat around £75,000 at the mid-point of the market in 2026, with senior profiles near £95,000 and the top decile above £125,000 in cash. Independent aggregators land in the same band (Glassdoor median ~£79k, 90th percentile ~£128k), which means an offer built below this range simply won't convert in London. Nationally the picture is softer — see our full UK technical recruiting coverage for the wider market.
The implication for hiring is speed. The UK average time to hire is about 4.9 weeks and specialist London roles often run longer [StandOut CV; NatWest Mentor, 2026]. ON3 returns a qualified shortlist in 24 to 48 hours and a median hire in under 30 days, which in this market is the difference between landing your first choice and settling for whoever is still available.
If you are still deciding how to run the search, we compare the real cost, speed and risk of an agency versus in-house hiring, and of AI-led recruiting versus a traditional agency.
What to budget, by role and seniority
Indicative annual base salary for London, from ON3's profile index. Use it to pitch an offer that actually lands.
| Role | Junior | Mid | Senior |
|---|---|---|---|
| Backend | £31k–48k | £64k–101k | £79k–121k |
| Full-stack | £32k–45k | £45k–75k | £70k–100k |
| ML | £38k–54k | £52k–95k | £86k–142k |
| DevOps | £26k–40k | £50k–80k | £69k–102k |
Source: ON3 Works index of 1.7M+ UK and Spanish technical profiles, refreshed daily (2026). Indicative base salary; ML and payments-infra roles trend to the top of each band in London. Cross-checks: Glassdoor, IT Jobs Watch (2026).
Two tiers, one engineer-led standard
A precise note on the 24 to 48 hours: that shortlist is AI-screened and qualified, not yet engineer-interviewed. In Atelier, the senior-engineer interview follows before any candidate reaches you. No deposit, billed in GBP, free replacement inside 90 days. Both tiers, and worked fee examples, are set out on the pricing page.
From payments backend to deep tech
Strong in software across the stack, and growing fast in cybersecurity and deep tech (chips, HPC). Each role type is broken down in the profiles we cover directory. The most common London searches:
- Backend
- ML / AI
- Data
- DevOps / cloud
- Full-stack
- Frontend / React
- Platform
- Cybersecurity
- Engineering leadership
Who ON3 hires for in London
Two kinds of London buyer come to ON3. Teams worn down by traditional agencies charging a fortune want genuinely rigorous, technical vetting: profiles that are fully checked and fit the brief, not a stack of CVs. And fast-moving teams who never used agencies on cost try the Agentic model at 7%. In London, quality tends to matter even more than speed, which is exactly where the engineer-led vet earns its place.
One example from ON3's venture-capital channel: a YC-2023 company that raised a Series B in 2026 used ON3 to hire 12 technical staff, fast. CGI, which uses ON3 for 50+ hires a year, operates in the UK as well as Spain.
“ON3 Works has become my favourite external recruiting partner. They're fast, efficient, and bring us candidates already vetted, qualified, and ready to hire. They've made talent search easy for me and my team.”
— Gabriel Garcia, Vice-President Consulting Services, CGI
London hiring FAQ
How much do tech recruiters charge in London?+
How fast can you fill a backend role in London?+
What is the average backend engineer salary in London in 2026?+
What tech stacks are most in demand in London right now?+
How is London different from other UK tech markets?+
Hiring in London? Tell us who you need
Send us the role. You'll get a qualified shortlist in 24 to 48 hours, and for critical hires, a senior engineer who interviews every finalist.
Tell us who you need to hire →Sources & notes
ON3 figures (London salary bands and headline; 7%/20%, no deposit; 24 to 48h shortlist; <30-day median hire; 90.7% retention; 90-day replacement; 1.7M+ profile index; 67% of UK placements London-based; YC/Series-B and CGI references): supplied by ON3 Works. The £75k figure quoted in the market section is ON3's index mid-point; the ~£79k median cited in the FAQ is the blended figure including independent aggregator cross-checks.
UK time to hire (~4.9 weeks): StandOut CV; NatWest Mentor (2026). London salary cross-check (backend ~£79k median, ~£128k 90th percentile): Glassdoor; IT Jobs Watch (2026).
Note: the 24 to 48h shortlist is AI-screened-qualified, not yet engineer-interviewed; the engineer vet follows in Atelier. Salary figures are indicative and should be confirmed for a specific role.