Callosum careers
Callosum is hiring: 10 open roles as of November 13, 2026, none listed as remote, 100% of them staff level. Posted pay runs $136k–$259k. The roles ask most for LLMs, Python and distributed systems.
Which of Callosum’s 10 roles fit you?
Pick your team. landed reads each role against your resume and applies to the ones that fit.
- Security Lead - Member of Technical StaffLondon
- Research Engineer, Evals - Member of Technical StaffLondon
- Agent Runtime & Systems - Member of Technical StaffLondon
- ML Research Engineer - Member of Technical StaffLondon
- Evolutionary Optimisation - Member of Technical StaffLondon
Callosum operates at the level of systems, not models, to unlock orders-of-magnitude improvements in capabilities and cost.
Callosum is inAI native companiesArtificial intelligence
Open roles
10
Founded
2025
Headcount
28
Remote roles
0%
Hiring now · checked today
Callosum has 10 roles open right now.
landed applies to the ones that fit you on Callosum's own site, the hour they go live.
landed · Callosumautopilot on
Security Lead - Member of Technical Staff
London
Research Engineer, Evals - Member of Technical Staff
London
Agent Runtime & Systems - Member of Technical Staff
London
10 open
Open roles at Callosum
Checked on Callosum’s careers page
Security Lead - Member of Technical Staff
Callosum
London
Security Lead - Member of Technical Staff
London
Pay not posted
12w ago
Research Engineer, Evals - Member of Technical Staff
Callosum
London
Research Engineer, Evals - Member of Technical Staff
London
$136k–$259k
12w ago
Agent Runtime & Systems - Member of Technical Staff
Callosum
London
Agent Runtime & Systems - Member of Technical Staff
London
$136k–$259k
12w ago
ML Research Engineer - Member of Technical Staff
Callosum
London
ML Research Engineer - Member of Technical Staff
London
$136k–$259k
12w ago
Evolutionary Optimisation - Member of Technical Staff
Callosum
London
Evolutionary Optimisation - Member of Technical Staff
London
$136k–$259k
12w ago
Research Engineer, Benchmarking - Member of Technical Staff
Callosum
London
Research Engineer, Benchmarking - Member of Technical Staff
London
$136k–$259k
12w ago
Networking & Interconnect Systems - Member of Technical Staff
Callosum
London
Networking & Interconnect Systems - Member of Technical Staff
London
$136k–$259k
12w ago
Inference Performance & Deployment - Member of Technical Staff
Callosum
London
Inference Performance & Deployment - Member of Technical Staff
London
$136k–$259k
25w ago
Apply to Callosum with landed
Callosum hires through Ashby. landed applies on Callosum’s own Ashby form, with your résumé tailored and every question answered for the role.
- 1Add your résumé and the roles you want
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- 3It applies on Ashby. Review each one first if you like
Posted pay
Callosum salary by role
Across Callosum’s postings that list pay, the middle of the range runs $136k–$259k. The highest posted range right now is $136k–$259k for Research Engineer, Evals - Member of Technical Staff. Ranges are base pay as the company posts it.
| Role | Postings with pay | Posted range |
|---|---|---|
| Research Engineer, Evals - Member of Technical Staff | 1 | $136k–$259k |
| Agent Runtime & Systems - Member of Technical Staff | 1 | $136k–$259k |
| ML Research Engineer - Member of Technical Staff | 1 | $136k–$259k |
| Evolutionary Optimisation - Member of Technical Staff | 1 | $136k–$259k |
| Research Engineer, Benchmarking - Member of Technical Staff | 1 | $136k–$259k |
| Networking & Interconnect Systems - Member of Technical Staff | 1 | $136k–$259k |
| Inference Performance & Deployment - Member of Technical Staff | 1 | $136k–$259k |
| Inference Engine Development - Member of Technical Staff | 1 | $136k–$259k |
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Frequently asked
Is Callosum hiring right now?
Yes. Callosum has 10 open roles live on its own careers page today, and the list above refreshes daily.
Does Callosum hire remote?
Almost all of Callosum’s open roles are office based right now.
What does Callosum pay?
Across the Callosum postings that list pay, the middle of the range runs $136k–$259k.
How do I apply to Callosum?
Callosum takes applications on Ashby. Every role above links to Callosum’s own application. Or let landed apply for you: it fills the company’s form with your profile and writes the answers for each role.
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