Senior Fullstack Engineer (Moderation)

Stream powers real-time Chat, Video, Activity Feeds, and AI Moderation for more than 1 billion end users across 4,000+ apps, from Strava and Bumble to eBay and Patreon. Our platform processes billions of API requests per month and supports applications with millions of concurrent users, while delivering highly reliable, low-latency services and a great developer experience.

We're looking for a Senior Full Stack Engineer I to join Stream on our mission of elevating the quality of apps for billions of users globally. You'll own the backend of our AI Moderation product: building new capabilities and making the Go services behind them cleaner, faster and more reliable.

This is a full-time role, hybrid with 3 days a week in our Toronto co-working space.

You'll join our five-person Moderation team, which builds the product customers use to detect, review and act on harmful content in their apps. The role leans backend. Dedicated frontend engineers own the moderation dashboards, and you'll own the Go services, data model and integrations behind them, stepping into React when a feature spans the stack. You'll work closely with the team lead, our other Toronto-based engineer, Infrastructure, and the Customer Success and Support teams, and directly with customers' trust and safety and engineering teams.

Here's the honest current state: the product has grown fast and the backend has grown with it. There's real cleanup, refactoring and simplification to do, and you'll have the room to do it well. You'll also give the team coverage in North American hours, which today rests largely on one engineer.

• Build new moderation features: design and ship Go services from database schema and API endpoints through to production rollout, including work on our new AI moderation flow.

• Clean up the backend: refactor existing moderation services, reduce technical debt, simplify code paths and raise test coverage.

• Improve reliability and performance: strengthen alerting and observability, and fix scaling and latency issues in the moderation pipeline.

• Own third-party integrations: maintain and extend the AI and moderation providers that plug into the pipeline.

• Keep production healthy: diagnose defects to root cause and take part in on-call, with a focus on North American hours.

• Work with customers: troubleshoot their issues directly and bring what you learn back into the roadmap.

• Work across the stack when needed: ship React changes alongside the frontend engineers and review your peers' code.

You're a backend engineer at heart who is comfortable picking up frontend work when a feature needs it. You enjoy leaving a codebase better than you found it, and you'd rather simplify a service than add another layer to it. You like owning problems end to end, including the ones that show up in production or in a customer conversation.

You probably won't enjoy this role if you want a pure frontend position, a large team with a fixed process, or a job with no on-call. The team is small, the product is moving fast, and North American coverage is part of the job.

• 3+ years of professional software engineering experience, mostly on the backend.

• Solid backend experience in Go, Python or a comparable language, and willingness to work in Go. We run a 10-week internal Go onboarding programme.

• Experience designing REST APIs and relational data models (ideally Postgres), and working with Redis.

• A track record of shipping features used at scale and of refactoring and improving existing production systems.

• Working knowledge of React and TypeScript or JavaScript.

• Experience with automated testing across client and server code.

• Comfort working with customers and handling production incidents.

• Exposure to trust and safety, content moderation or policy enforcement products.

• Professional experience with Go.

• Experience with GCP or another major cloud provider.

• Experience integrating LLM or ML-based services into production systems.

• Message queue experience.

• Full-text search experience.

• Open-source contributions.

• Scope: you'll own the backend of a product area, with the room to clean up and reshape it.

• Impact: AI Moderation is one of Stream's growth products, and you'll help ship its new AI moderation flow and the features that come after it.

• Stack: Go, Postgres, Redis and React on GCP, with Claude, Cursor and ChatGPT Codex as everyday tools.

• Starting point: a small team where your work is visible from week one, and a second Toronto engineer to work with closely.

We're a Series B company with offices in Boulder, Amsterdam, Skopje and Toronto, and a team of 140+ people from 37 nationalities. We're backed by Felicis Ventures, GGV Capital, 01 Advisors, Techstars, and Arthur Ventures, with angels including Dick Costolo (ex-CEO of Twitter), Olivier Pomel (CEO of Datadog), Tom Preston-Werner (co-founder of GitHub), and Nicolas Dessaigne (co-founder of Algolia).

We'll be straight with you: a startup is more demanding than a large company. There's no fixed playbook, you'll own things end to end, and you'll sometimes pick up work outside your title. That's also what makes it a fast place to grow. If you want real ownership and high scale more than structure and a set career ladder, you'll feel at home here.

• A base salary of CAD 100,000 to 127,998 per year

• Stream employees enjoy some of the best job benefits in the industry:

  • A team of exceptional engineers

  • The chance to work on OSS projects

  • 20 days of PTO first year of employment, 24 days starting your second year

  • Company equity

  • Extended Healthcare

  • Dental benefit

  • Long & Short-Term Disability

  • Life Insurance

  • Fitness stipend

  • A Macbook Pro provided

  • A Learning and Development budget

  • The opportunity to attend or present to global conferences and meetups

  • The possibility to visit our offices in Boulder, CO and Amsterdam, NL

Stream is a casual, transparent team that aims high and supports each other. In engineering, we care about ownership and quality, and our goal is to ship stable software. Management stays hands-on, with less middle management and more time spent doing the work. If that sounds like the environment you want next, apply now.

Stream is an equal opportunity employer and welcomes applications from all qualified candidates. We don't discriminate based on any ground protected by the Ontario Human Rights Code. Accommodation is available on request for candidates taking part in all parts of the selection process.

This posting is for an existing vacancy. We don't use AI to screen, assess or select applicants. You must be legally entitled to work in Canada; we can't offer visa sponsorship or relocation for this role.

Hybrid office policy: applicants based (or relocating to) one of our office locations are expected to work according to the applicable local office attendance policy.

Equal opportunity employer statement: Stream provides equal employment opportunities to all employees and applicants for employment and prohibits discrimination and harassment of any type without regard to race, color, religion, age, sex, national origin, disability status, genetics, protected veteran status, sexual orientation, gender identity or expression, or any other characteristic protected by federal, state or local laws.

This policy applies to all terms and conditions of employment, including recruiting, hiring, placement, promotion, termination, layoff, recall, transfer, leaves of absence, compensation and training.

Note for external recruiters: We currently have this role covered and do not accept unsolicited agency resumes. We are not responsible for any fees related to unsolicited resumes.