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The End of Manual Debugging

In this episode of Founder Firesides, YC General Partner Aaron Epstein talks to Sherwood Callaway, founder of Sazabi (P26), who exited his first YC company and is coming back through YC for a second time. Sazabi is an AI-native observability platform that replaces tools like Datadog, letting engineers ask plain-English questions about their production systems instead of digging through dashboards. They discuss why logs are the only telemetry you need, lessons from building a company that didn't play to his strengths, and why maintaining software is AI's biggest untapped opportunity. Apply to Y Combinator: https://www.ycombinator.com/apply Work at a startup: https://www.ycombinator.com/jobs Chapters: 00:00 — Back to YC for a second time 00:24 — The AI tool fixing production bugs 01:36 — “Logs are all you need?” 03:43 — Inside observability at Brex 07:42 — Starting a healthcare startup 12:21 — When the first startup unraveled 17:02 — The insight behind Sazabi 22:51 — Returning to YC 27:00 — Lessons for founders + hiring

Aaron EpsteinhostSherwood Callawayguest
Mar 26, 202629mWatch on YouTube ↗

At a glance

WHAT IT’S REALLY ABOUT

Sazabi bets AI-native observability makes manual debugging largely obsolete forever

  1. Sazabi positions itself as an AI-native successor to Datadog/Sentry, letting engineers ask natural-language questions to quickly identify root causes, affected customers, and responsible commits during production incidents.
  2. The company’s central “logs are all you need” thesis argues AI makes unstructured logs newly machine-readable, reducing the need for separate metrics and traces instrumentation and simplifying observability adoption.
  3. Callaway’s background building infra and observability at Brex shaped his view that production is inherently unpredictable and the core job is rapid response, not perfect pre-release prevention.
  4. He reflects on Opkit (his first YC company in healthcare voice AI) as a misalignment with founder strengths and motivation, emphasizing the importance of building in areas of personal expertise and enjoyment.
  5. Returning to YC is framed as a speed and distribution strategy—imposing shipping discipline, accelerating go-to-market, and leveraging the YC network where every software company needs an observability solution.

IDEAS WORTH REMEMBERING

5 ideas

AI shifts observability from manual forensics to conversational diagnosis.

Sazabi’s promise is that engineers can query production (“Why is production down?”) and get synthesized answers—turning debugging work from dashboard spelunking into guided investigation and remediation.

A logs-first approach is a deliberate bet on simplicity and adoption.

By rejecting the traditional three pillars, Sazabi argues teams can avoid heavy instrumentation overhead; logs are easiest to produce and read, and AI can extract structure and meaning that older tools couldn’t.

Observability exists because pre-production certainty is impossible.

Callaway emphasizes that tests, QA, and static analysis help, but production behavior is inherently surprising; the winning strategy is readiness and fast feedback loops once real traffic hits.

Founder-market fit can be engineered—but it’s expensive in time and morale.

Opkit shows a team can become credible in a domain over years, yet still suffer if the work doesn’t align with strengths or long-term desire; sunk cost can keep founders in the wrong game.

The bigger opportunity is maintaining software, not writing it.

He contrasts tools like Cursor (new code generation) with the ongoing burden of operating systems in production, positioning maintenance automation and “self-healing software” as the larger surface area.

WORDS WORTH SAVING

5 quotes

“Logs are all you need.”

— Sherwood Callaway

“Every time there's an outage in production… I would spend hours digging through dashboards and log searches… and eventually I might get to the root cause, maybe not.”

— Sherwood Callaway

“Nothing really prepares you for production.”

— Sherwood Callaway

“We were building a futuristic AI product… and then when I would go to debug it… it was the same painful manual experience that I've had for my entire career.”

— Sherwood Callaway

“When I start this new company, it's gonna be fun.”

— Sherwood Callaway

AI-native observability and agentic debugging“Logs are all you need” vs. three pillars (logs/metrics/traces)Brex infrastructure hypergrowth and Kubernetes microservicesProduction reality and incident response philosophyOpkit: healthcare voice AI pivot and founder-market fit lessonsWhy repeat YC: acceleration, culture, and distributionHiring profile: high-agency engineers; infra/data + design-forward product

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