Senior/Staff+ Software Engineer

Seenthis AB; Stockholms kommun; On-site; SEK 900,000 - 1,500,000; Full time

Job summary

SeenThis in Stockholm is seeking a Senior/Staff+ Software Engineer to own problems end to end, from discovery to production, across distributed systems and AI-powered workflows.

You will work with TypeScript/Node, build scalable infrastructure, and apply guardrails for reliable AI-driven product features, while keeping a strong focus on quality and teamwork.

You’ll collaborate with cross‑functional teams, mentor others, and shape the engineering roadmap in a fast‑paced, international environment.

Qualifications

• Own complex systems end to end from discovery to production.
• Design scalable distributed services with observability.
• Ship and iterate AI-driven product workflows with guardrails.

Responsibilities

• Take a problem from discovery through to shipped solution and stay with it through launch and iteration.
• Own the full lifecycle: design, build, ship, operate, and iterate; weigh tradeoffs and guide architecture.
• Design systems that scale: distributed services with observable health and billing accuracy.
• Build AI into real product workflows: evals, guardrails, tracing, human-in-the-loop review.
• Raise the engineering bar through code review, mentoring, and technical direction.

Skills

Distributed systems

TypeScript

Node.js

LLM features

AI in production

Full-stack fundamentals

Tools

Claude Code

Codex

Job description

Senior/Staff+ Software Engineer

Build the systems that scale video advertising on the open web. Get the workflow right first, then use AI to help it run.

Most ad budgets flow to a few closed platforms for one reason: they make it easy. Buying video on the open web should be just as easy. At SeenThis, we're turning years of hands‑on campaign delivery into products that automate the right work while keeping people in control.

This is a senior‑to‑staff+ role for engineers who can take real product problems from ambiguity to production. You'll work across distributed systems, product workflows, LLM‑powered automation, and the operational details that make the whole thing reliable at scale.

About SeenThis

The open web has massive untapped advertising potential, but video has historically underperformed here. SeenThis is changing that. As a video advertising partner, we prove the open web delivers exceptional results, capturing more attention with cost‑effective video that keeps publishers profitable and the internet independent. Since 2017, we've served billions of streams for 5,000+ brands across 50+ countries. We believe brands deserve reach wherever audiences are, publishers deserve sustainable revenue, and the internet deserves to stay open.

Our team of 130+ employees works globally from offices in Stockholm, Oslo, London, Paris, Singapore, Hong Kong, New York, and Sydney. We're expanding across all teams and constantly seeking new colleagues who want to make real impact in a fast‑moving, collaborative environment where innovation happens daily.

Do you want to be part of our journey, where we dare to discover, own it, and win together? Join SeenThis!

About the role

You’ll join our R&D org to own problems end to end with your team. We re‑team when it makes sense and work across the portfolio, so this role is not locked to one product area. Where you start, and where you grow next, depends on your strengths, interests, and where the business needs senior ownership most.

The three streams you may work across are:

Core Tech. The streaming, delivery, and measurement technology at the foundation of everything we do, handling billions of events a day.

Studio. Our creative production tool, where teams build, adapt, and launch campaigns, and the engine behind our own managed production.

Creative Manager. The orchestration layer and system of record for media plans, orders, approvals, creative delivery, and reporting.

You’ll work in a small team of peers: flat, fast, close to customers, close to the model, and serious about quality. You own problems, not tickets, and you own them together. We measure ourselves on whether what we ship changes behaviour.

We’re hiring across senior to staff+ level. The level follows your experience and the scope you’re ready to own, and we calibrate it with you.

Applied AI is central to the role, but it comes second on purpose. We get the product and workflow right for people first, with solid engineering and a strong human‑in‑the‑loop experience. Then we apply AI to automate the work, one proven step at a time. The goal isn’t to add AI for its own sake. It’s to build systems where the product handles more of the work, people set intent, review exceptions, and stay in control.

Agents can now take on a meaningful share of implementation work, which changes the job. The value is in judgment: framing the problem, setting the guardrails, and knowing what good looks like, so you can tell solid work from a confident mistake. We already build this way, with agents on most tasks through Claude Code and Codex, in‑house skills that teach them our conventions, and an AI reviewer on every pull request.

What you’ll do

• Take a problem from discovery through to something shipped and working, with your team, and stay with it through launch and the iteration after.
• Own the full lifecycle: design, build, ship, operate, and iterate. Weigh tradeoffs in the open, make the architectural calls, and bring peers with you.
• Design systems that scale: distributed services where a dropped or double‑counted event becomes a billing error, with the observability and operational care to keep them healthy.
• Build AI into real product workflows: evals, guardrails, tracing, human‑in‑the‑loop review, and the state and tool contracts behind agents that hold up in production.
• Raise the engineering bar through code review, mentoring, technical direction, and the way you work.

Qualifications

• Senior level: you’ve owned complex systems end to end and shipped them into production.
• Staff+ level: you’ve led ambiguous, multi‑month technical problems, made strong architectural calls, and brought others with you.
• You have very strong engineering fundamentals. You design distributed systems that scale, weigh tradeoffs, and instrument for observability.
• You have full‑stack range. We build in TypeScript and Node, but fundamentals matter more than the stack. You pick up what the problem needs.
• You’ve shipped LLM or agent features in production, beyond basic prompting: tool use, retrieval, orchestration, evals, and guardrails. You have an intuition for where models are reliable and where they need constraints, review, or another approach entirely.
• You drive alignment across technical and non‑technical people, and work out what matters most rather than waiting for a spec.
• You have high ownership and low ego. You care about quality, lift the people around you, and want the work to matter.
• You already work AI‑native: you direct agents, judge their output, and build your own tooling, while still being able to reason through a problem and debug without them. We’ll ask for concrete examples of how you work this way.

Bonus if you have experience with

• The platform layer behind an AI product: the orchestration, eval infrastructure, and tracing that other engineers build on, not only the features on top.
• Partnering with data or ML teams to productise model capabilities, or diagnosing and fixing model failure modes in production.
• High‑throughput event pipelines, streaming data, or real‑time systems.
• Our wider stack: BigQuery, ClickHouse, Airflow, and a multi‑cloud footprint across AWS and GCP.
• Third‑party platform APIs, such as Meta, ad servers, or DSPs, integrated and running in production.
• Ad tech, martech, creative tooling, or another commercially messy domain.

Application

If you’re close on most of this and strong where it counts, we’d rather hear from you than not.

As we review applications and interview on a continuous basis, please apply as soon as possible. Due to the high volume of applications received, we are unable to provide personalized feedback prior to the interview stage. Thank you for understanding!

Please note: we’re in our summer holiday period. Response times may be a little longer than usual, and we will get back to all candidates with feedback once the holiday period is over. Thank you for your understanding and patience.

We conduct background checks on all SeenThis‑hires to comply with our customers and protect business‑critical information.

We look forward to welcoming you to SeenThis!