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Celara

Posted 1 month ago

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Backend Developer SR (AM - BE - 20260512)

Buenos AiresHybridContract

AI Summary

Senior backend engineer focusing on building a new AI-powered purchase platform. Leads design, implements provider connectors, and ships end-to-end AI features end-to-end in a fast-paced, hands-on environment.

About this role

We're looking for a modern, AI-empowered engineer — strong fundamentals, opinionated about good design, and fluent in agentic tooling — to help build and launch a new digital purchase platform. Someone who codes fast, leads by example, and can hold their own in product conversations as easily as in technical ones.

The project is for a major company modernizing how customers buy online — standing up a modern stack to run the full purchase flow online, end-to-end. We're building a brand-new back-end: a modern integration layer to multiple third-party provider APIs, the AI plumbing to power agentic features across the funnel, and an agent-facing dashboard ("Agent Co-Pilot") that lets human agents see live shoppers in real time and jump into the conversation when needed. The first AI lighthouse is a customer-facing chat assistant tied into that same plumbing — pricing, configuration, eligibility checks, hand-off to a human. This is a 3-month foundation build with a senior, hand-picked team, kicking off ASAP.

Responsibilities:

  • Build and own provider connectors on the new integration framework — auth, retries, webhooks, observability, etc.

  • Lead by example on technical direction — drive design discussions, unblock the team, and own the hardest pieces of the stack.

  • Partner with the client's PM and product stakeholders in 1–2 week sprints — daily standups, weekly demos — pushing back on scope, proposing better solutions, and translating product intent into clean technical bets.

  • Ship AI features end-to-end against the lighthouse roadmap (chatbot, Agent Co-Pilot, plumbing for what comes next).

  • Set engineering practices the permanent team will inherit — clean code, tests, AI-generated docs, CI/CD, eval harnesses on LLM-touching code paths.

  • Pair with the architect and tech lead on cross-cutting design; mentor through code review.

Why It's Interesting:

  • You'll be working alongside a talented, hand-picked senior team.

  • Greenfield rebuild, not legacy maintenance. We're migrating off the current vendor's platform onto a new, clean, modern codebase. You'll set the future patterns the new system gets built on.

  • Best-in-class agentic-AI SDLC from day one. You'll help design the patterns — Claude Code across the full SDLC, AI-generated documentation, evals on every LLM-touching feature, observability built in.

  • Interesting consumer AI features — a live-shopper dashboard, an in-funnel AI chatbot, and the plumbing for everything that comes after.

  • Path to lead the team going forward. This 3-month build is Phase 1. The client will then ramp a permanent squad on top of the codebase you helped create — clear path into the lead role.

Skills Required:

  • 6+ yrs building production back-ends; comfortable owning a service end-to-end

  • Strong in a modern typed stack (TypeScript/Node or Python/FastAPI)

  • Built and maintained third-party API integrations at scale (auth, retries, rate limits, webhooks, idempotency)

  • Hands-on with agentic AI tooling — Claude Code in daily SDLC, LLM API integration, prompt + eval discipline

  • Opinionated and direct — pushes back on scope, holds the bar on docs and tests

  • Cloud + IaC (AWS or GCP, Terraform, Docker, CI/CD pipelines)

  • Bonus: VLM/RPA or browser-automation experience for provider fallback paths

Skills

Agentic AI ToolingAPI IntegrationsAuthAWSCI/CDClaude CodeDockerDocumentationEvaluation HarnessesFastAPIGCPIdempotencyLLM APIsNode.jsObservabilityPrompt EngineeringPythonRetriesSDLC ToolingTerraformTestsTypeScriptWebhooks

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