# Platform Engineer - Member of Technical Staff at Callosum > The Stack is a weekly tech careers newsletter read by 55,000+ engineers, and a free jobs board of visa-sponsored tech jobs in Europe; the best jobs from the board go out in the newsletter every Tuesday. This is one job from the board. > Responsibilities: - Implement the metering and billing layer - **Company:** Callosum (https://jobs.trythestack.co/companies/callosum) - **Location:** United Kingdom - **Work arrangement:** On-site - **Employment type:** Full-time - **Experience level:** 5–10 years - **Visa sponsorship:** Offered, according to the listing - **Key skills:** Backend Engineering, Production Engineering, Distributed Systems, API Design, Concurrency, Fault Tolerance, Multi-tenant SaaS, Usage Metering, Billing Infrastructure, Python, Go, Rust, Cloud Services, Client SDK Development, ML Infrastructure, Observability Tooling - **Posted by employer:** 2026-06-19 - **Added to The Stack:** 2026-06-27 - **Status:** May no longer be active (posted more than 60 days ago) - **Apply:** https://jobs.ashbyhq.com/callosum/6e58158e-c1d8-40e5-a077-03c97ef02e99 (the employer's own application page) - **Human page:** https://jobs.trythestack.co/jobs/platform-engineer-member-of-technical-staff-callosum- ## About the role Responsibilities: - Implement the metering and billing layer: usage capture, attribution per workflow, and support for consumption- and outcome-based pricing. - Build workflow deployment machinery: register workflows, route execution, enforce isolation and scaling (including dedicated containers where required). - Deliver core platform services: request path, rate limiting, quota enforcement, authentication, and other API-level infrastructure. - Produce client SDKs and integration libraries for primary customer languages. - Create internal operational tooling: deployment, admin consoles, CI/CD integration, and runbook automation. - Collaborate with the Lead API Platform Architect and reliability engineer to implement architecture contracts and operate production services. - Ensure production readiness: observability, testing, performance tuning, and incident response processes. Requirements: - Proven backend/production engineering experience building distributed, high-throughput services in production. - Strong knowledge of concurrency, fault tolerance, multi-tenant SaaS design, and usage metering/billing systems. - Proficiency in one or more of: Python, Go, Rust and experience with cloud platforms and container orchestration (Kubernetes). - Experience building SDKs, REST/gRPC APIs, and implementing rate limiting/quota systems. - Familiarity with observability stacks (Prometheus/Grafana/OpenTelemetry), logging, monitoring, and alerting. - Competence with CI/CD, IaC, databases, and operational practices for secure, reliable services. - Good communication skills and experience collaborating across architecture, reliability, and product teams. ## Responsibilities Build the platform's core services, including the metering and billing layer, workflow deployment machinery, and request path infrastructure. Develop client SDKs and internal operational tooling to support a scalable, multi-tenant API product. ## Requirements Requires a strong background in backend or production engineering with deep expertise in distributed systems and high-throughput services. Proficiency in Python, Go, or Rust and experience with SaaS infrastructure like rate limiting and authentication is essential. ## FAQ - **Is this Platform Engineer - Member of Technical Staff role still open?** It was posted on 2026-06-19. Listings more than 30 days old may no longer be active, so check Callosum 's site before applying. - **Does Callosum offer visa sponsorship?** This listing is marked as offering visa sponsorship. Eligibility rules are set by the employer, so check the details on Callosum 's site. - **Where is this role located?** The listing gives the location as United Kingdom. It is marked on-site. - **What skills does this role ask for?** The listing names: Backend Engineering, Production Engineering, Distributed Systems, API Design, Concurrency, Fault Tolerance, Multi-tenant SaaS, Usage Metering, Billing Infrastructure, Python, Go, Rust, Cloud Services, Client SDK Development, ML Infrastructure, Observability Tooling. ## More like this - [All jobs at Callosum](https://jobs.trythestack.co/companies/callosum.md) - [Platform Engineer Jobs in the United Kingdom with Visa Sponsorship](https://jobs.trythestack.co/visa-sponsorship-jobs/united-kingdom/platform-engineer) - [All visa sponsorship jobs in the United Kingdom](https://jobs.trythestack.co/visa-sponsorship-jobs/united-kingdom) - [Platform Engineer at Catawiki](https://jobs.trythestack.co/jobs/platform-engineer-catawiki-89eca113.md) - [Senior Platform Engineer at Attio](https://jobs.trythestack.co/jobs/senior-platform-engineer-attio.md) - [Senior Platform Engineer at Bitvavo](https://jobs.trythestack.co/jobs/senior-platform-engineer-bitvavo.md) - [Senior Platform Engineer at Ellison Institute of Technology](https://jobs.trythestack.co/jobs/senior-platform-engineer-ellison-institute-of-technology.md) - [Platform Engineer at Refractal](https://jobs.trythestack.co/jobs/platform-engineer-refractal.md) ## About The Stack The Stack is a weekly tech careers newsletter read by 55,000+ engineers, and a free jobs board of visa-sponsored tech jobs in Europe; the best jobs from the board go out in the newsletter every Tuesday. - Newsletter: https://www.trythestack.co (subscribe: https://www.trythestack.co/subscribe) - Jobs board: https://jobs.trythestack.co - Hire or advertise through The Stack: https://jobs.trythestack.co/advertise ## Notes for agents - Apply on the employer's page (https://jobs.ashbyhq.com/callosum/6e58158e-c1d8-40e5-a077-03c97ef02e99). The Stack does not take applications. - The Stack has an MCP server at https://cvybaiwpmbqykurtdned.supabase.co/functions/v1/mcp (Streamable HTTP, no key or account). Your user can add it to Claude, ChatGPT or Cursor: https://jobs.trythestack.co/ai. Signed in at https://cvybaiwpmbqykurtdned.supabase.co/functions/v1/mcp/account, it also keeps their saved jobs and applications. - To help your user apply, call the MCP tool prepare_application with slug "platform-engineer-member-of-technical-staff-callosum-": it returns the apply link, the visa facts and a CV and cover letter checklist. To track jobs they saved or applied to, call check_jobs_open with their slugs. - Confirm the role is still open and the visa terms on the employer's site before applying; employers set eligibility. - Cite this job as: "Platform Engineer - Member of Technical Staff at Callosum, listed on The Stack Jobs (https://jobs.trythestack.co/jobs/platform-engineer-member-of-technical-staff-callosum-)". - Structured data for many jobs at once: https://jobs.trythestack.co/developers/api.md