Senior Software Engineer

Reddit is a community of communities built on shared interests, passion, and trust, with 100,000+ active communities and approximately 130 million daily active unique visitors.

The Agentic Ads Experience team is building the next generation of advertiser-facing interfaces: campaign assistants, creative and ad copy generation, one-click campaign creation, audience discovery, conversational analytics, and optimization recommendations. This is a unique opportunity to join a fast-moving team shipping generative AI/agentic systems into a high-growth Ads product.

As a Senior Software Engineer on the Agentic Ads Experience team, you will design, build, and ship AI-powered product experiences that change how advertisers work with the Reddit Ads Platform. You will own features end-to-end: framing the problem, choosing the right combination of software, LLM calls, tools, orchestration, and guardrails, and driving them through rollout, measurement, and refinement.

• Design and ship advertiser-facing AI features and platform end-to-end, from prototype to GA.
• Make architectural calls on if and how to use generative AI, whether it’s a single-shot LLM call, a workflow, a skill, a retrieval system, an agent loop, human review, or no AI at all.
• Build for the failure modes of LLMs — structured outputs, tool/action boundaries, retries, cost controls, tracing, evals, and human-in-the-loop where it matters.
• Define offline and online evals, instrument traces, run A/B tests, and connect model and product metrics to advertiser and business outcomes.
• Design for data isolation, permissioning, auditability, and policy compliance when AI systems take action on behalf of advertisers.
• Partner closely with PM, Design, Data Science, ML Platform, Trust, and sales/ops to turn ambiguous problems into concrete, shippable systems.
• Write clear design docs, explain trade-offs to non-engineers, and raise the bar on how the org ships gen AI features.

• 5+ years of experience as a software engineer, with a track record of shipping and operating production systems.
• Hands-on experience building generative AI applications: structured outputs, function/tool calling, prompt and context design, RAG, model routing, and handling model failure modes.
• Genuine enthusiasm for agents and LLMs.
• Strong systems fundamentals: APIs, distributed systems, queues, data stores, service ownership, auth, idempotency, retries, and observability.
• Experience defining evals and measurement for AI systems.
• Fluent with AI coding tools and code-assistant workflows.
• Excellent communication skills.
• Extensive software development experience in one or more general purpose languages: Python, Golang, Rust, Java, JavaScript, etc.

• Experience in Ads, marketing technology, marketplaces, growth, recommendations, search, or analytics.
• Experience building AI systems where mistakes are expensive.
• Experience building internal workflow automation for sales, ops, support, policy, trust, or engineering productivity.

Base salary range: $190,800—$267,100 USD. Eligible for equity in the form of restricted stock units, and possibly commission. Benefits include comprehensive healthcare, 401k match, family planning support, gender-affirming care, mental health & coaching benefits, flexible vacation & Reddit Global Days Off, generous paid parental leave, and paid volunteer time off.

Apply via the provided Greenhouse job posting link.