Principal Engineer

About The Role:

We're an advertising company that lives or dies by how well we connect to the outside world. We integrate with the major social and ad platforms (Meta, Google, TikTok, LinkedIn, Snap, and more) and wire them into our internal systems for billing and reporting. Data moves constantly and in both directions, at scale, and a meaningful part of our estate is legacy. You'll own the technical direction that keeps all of this coherent, resilient, and evolvable - and you'll stay close enough to the code to prove it.

This is the top of our individual-contributor ladder. You won't have direct reports; your leverage comes from setting direction, building the hard parts yourself, writing the decisions down, and getting engineers and leadership to build behind them. This is not a role that only draws diagrams - you'll ship production code on the riskiest paths, cut the spike that de-risks a migration, and go deep in the incidents nobody else can crack. We work across PHP, Go, Python, TypeScript, and JavaScript; PHP and Go are both first-class and here to stay, and the right tool for a problem can land in either. You'll be the person who decides where new capability lands, how legacy gets retired, and how we absorb the constant churn of third-party APIs without breaking delivery.

What You'll Own:

• The integration architecture for ingesting from and pushing to external ad/social platforms - versioning, rate limits, backfills, idempotency, webhooks, and graceful degradation when a partner API changes underneath us.
• The data architecture for information flowing between platforms and internal systems: pipelines, reconciliation, contracts between services, and the path from operational data to reporting.
• A pragmatic strategy for modernizing the legacy estate - strangler-fig migrations, clear service boundaries, and sound judgement about which language and pattern fit each problem - carried far enough into code that teams can follow the pattern.
• The engineering bar for integration and data work: the reference implementations, patterns, and standards the org builds against, ratified through the technical committee.

What You'll Do:

• Set the technical direction for new products and major changes, and stay the technical decision-maker through build and post-launch - with the authority to course-correct when implementation drifts, and the habit of being in the codebase to catch the drift early.
• Build the hard parts yourself. Write production code on the riskiest, highest-leverage paths; prototype the uncertain approach to turn an argument into evidence; build the reference implementation others extend.
• Turn intangible trade-offs - partner API risk, team capability, long-term scalability, cost of change - into clear, written decisions (ADRs) that leadership and the technical committee can sign off on.
• Define service and data contracts, integration patterns, and resilience strategies that survive third-party API deprecations and outages.
• Go deep when it breaks: lead diagnosis on the gnarliest production incidents and performance regressions, and land the fix and the systemic follow-up.
• Identify the infrastructure (compute, data, messaging, observability) needed to meet current and near-future goals.
• Raise the bar through others: mentor engineers and tech leads, set the standard in code review, and drive cross-functional decisions across engineering, product, security, and operations - through influence, not line management.
• Evaluate third-party and vendor solutions against our integration and data requirements.
• Monitor systems against performance and business benchmarks and escalate with concrete recommendations.

What We're Looking For:

• Substantial experience as a staff/principal engineer (or equivalent) on integration-heavy, data-heavy systems - ideally where you didn't control the external APIs.
• Still hands-on. You lead by building, and you're demonstrably strong in production code, not only in design.
• Depth in at least one of PHP, Go, or Python, and comfort across a polyglot estate (TS/JS on the front).
• A track record of modernising legacy systems incrementally without halting delivery.
• Fluency in integration and data patterns: idempotency, eventual consistency, rate limiting, queuing, backfills/reconciliation, API versioning.
• A history of driving technical decisions through influence rather than authority - getting senior leadership and peer engineers to commit to a direction, and backing it with working code.

Nice To Have:

• Experience with ad/martech platform APIs (Meta Marketing, Google Ads, TikTok, etc.).
• Data warehouse / analytics pipeline experience (e.g. BigQuery).
• Multi-region, multi-currency, or high-volume billing/reconciliation backgrounds.