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Smallest.ai is hiring a Senior Software Engineer for Systems & Reliability to own services across their real-time voice platform. You will take full ownership of services from design through production, including writing code, testing, deployment, and ongoing operations. The role emphasizes end-to-end responsibility: you won't hand off work at merge, but instead maintain accountability through production.
The systems you'll work on power real-time voice interactions where latency is critical. Behind the scenes are GPU inference workloads for text-to-speech and speech recognition running across AWS regions, multi-tenant APIs, concurrency controls, billing systems, webhooks, and workflow orchestration. The tech stack includes Python, TypeScript, and Go running on Kubernetes in AWS, with supporting infrastructure including Redis, MongoDB-compatible stores, Postgres, ClickHouse, RabbitMQ, and Temporal.
Key responsibilities include: defining and establishing service-level objectives (SLOs) for customer-facing latency, availability, and correctness; writing maintainable, understandable code; comprehensive testing (unit, integration, load, fault-injection); owning CI/CD pipelines, deployments, rollbacks, schema migrations, and infrastructure-as-code changes; creating dashboards, alerts, and runbooks; participating in on-call rotations and incident response; investigating customer-impacting failures directly; and turning recurring incidents into better controls and automation.
The team is strengthening reliability practices for the next growth phase. Current challenges include defining SLOs for services without clear targets, replacing misleading health signals with customer-outcome-focused monitoring, improving logging and alerting, making testing and operational readiness consistent, and addressing reliability gaps alongside new feature development. You'll balance delivery speed with production readiness, surface risks early, and propose practical trade-offs.
Smallest.ai values demonstrated engineering ability over credentials. The role requires strong fundamentals in systems thinking, including deep understanding of processes and operating systems, memory management, storage and durability, networking (TCP, DNS, TLS, NAT), concurrency and distributed systems, language runtimes, data systems, and reliability engineering. You should be comfortable with SLIs, SLOs, error budgets, latency percentiles, and alerting on customer-visible symptoms. Clear writing, patience with unfamiliar code, and a habit of measuring before concluding are valued.
This is a hands-on role with substantial accountability. It includes on-call responsibilities, occasional incidents outside regular hours, customer escalations, and debugging across systems you may not have built. The company culture emphasizes honesty about knowledge gaps, sharing hypotheses early, taking responsibility for systemic improvements, starting with customer experience, using evidence (traces, profilers, query plans), respectful challenge of ideas, automation of repeated work, and moving with urgency.
The role is not suitable if you prefer narrowly scoped implementation tasks, consider responsibility complete at code merge, or expect testing and operations to be handled by separate teams.
REQUIREMENTS:
- Strong engineering fundamentals applicable to unfamiliar problems
- Deep understanding of: processes and operating systems (process creation, signals, file descriptors, namespaces, cgroups, PID 1, CPU throttling); memory management (virtual memory, page cache, swap, cgroup limits, OOM behavior); storage and durability (inodes, fsync, atomic operations, IOPS); networking (TCP states, timeouts, DNS, TLS, NAT, UDP trade-offs); concurrency and distributed systems (race conditions, locks, idempotency, delivery guarantees, retries, backoff, partial failures); language runtimes (event loops, garbage collection, Python GIL, memory leaks); data systems (indexes, query plans, transaction isolation, replication); and reliability engineering (SLIs, SLOs, error budgets, latency percentiles, alerting)
- Ability to explain and reason about systems-level concepts
- Clear writing and communication skills
- Patience with unfamiliar code
- Habit of measuring and using evidence before drawing conclusions
- Evaluation is based on demonstrated ability, not years of experience, titles, employers, degrees, or certifications
