Senior Backend Engineer, Vehicle and Device Integrations

About Gridio

Gridio is a European smart charging and energy flexibility platform. We help EV drivers cut charging costs by up to 50% by automatically optimizing charging during the cheapest and greenest hours. Our platform integrates directly with all major car brands through OEM APIs and works with any charger or energy supplier. We partner with utilities, OEMs, and energy companies including TotalEnergies, Enovos, and Ignitis to deliver smart charging and flexibility services that support a cleaner, more resilient grid.

The role

Behind every smart charge Gridio executes, there's a Go service negotiating with the API of a car company, a charger manufacturer, or a battery vendor. We integrate with roughly 48 of them: 20 EV brands, 12 charger brands, and 16 inverter and battery brands. Each one has its own quirks, its own definition of success and failure, and its own opinion on what OAuth should look like. Our integration layer turns all of that into one clean stream the rest of the platform builds on.

Each integration runs as its own ECS service, sharing a common engine and a common contract. Commands and measurements move over Kafka. Identity, customer, and data services are reached via gRPC.

We're hiring a senior engineer to own this codebase end to end: keep existing integrations healthy, ship new ones, evolve the platform underneath them, and be the technical anchor for everything that talks to a third-party vendor API.

What you'll own

•   Connector repo ownership. You are the directly responsible engineer for how new integrations are written, tested, and deployed.

•   New OEM integrations. Scope and deliver new vehicle, charger, and inverter integrations end to end. OAuth flows, token refresh, device metadata mapping, measurement streaming, command handling, deployment.

•   Production reliability. Own the health of the connector fleet across token refresh failures, rate-limit storms, OEM-side outages, schema drift, and credential rotation breakage. Participate in on-call rotation.

•   Architecture and platform work. Drive larger changes across Kafka topic design, credential storage (KMS, Secrets Manager, DynamoDB), Lambda fan-out, multi-region deployment, and protobuf schema evolution.

•   Security and credentials. Treat user OEM credentials as the crown jewels. Maintain safe OAuth2 and PKCE flows, secure storage and rotation, and least-privilege IAM per integration.

•   Collaboration and mentorship. Work with platform teams on contract changes, partner with product on which OEMs to prioritise, and mentor engineers contributing brand-specific integrations.

Required qualifications

•   5+ years of professional backend engineering, with substantial recent experience in Go (idiomatic Go, goroutines and channels, context propagation, error handling, profiling).

•   Proven track record integrating with third-party APIs at scale, including the messy parts: undocumented quirks, breaking changes, rate limits, flaky auth, regional differences.

•   Deep working knowledge of OAuth2, OIDC, and token-based authentication, including refresh flows, PKCE, and credential lifecycle management.

•   Hands-on experience with event-driven systems: Kafka preferred, or comparable (NATS, Kinesis, RabbitMQ), including consumer groups, partitioning, idempotency, and back-pressure.

•   Solid AWS experience: ECS or equivalent container runtime, Lambda, KMS, Secrets Manager, IAM, Cognito, CloudWatch.

•   gRPC and Protocol Buffers in production: defining services, evolving schemas without breaking consumers.

•   Comfortable with Terraform and containerized CI/CD (GitLab CI, GitHub Actions, or similar). Capable of changing a deployment pipeline, not just consuming one.

•   Strong production debugging skills: reading metrics (Prometheus), traces (OpenTelemetry), and structured logs to localise problems in a distributed system you didn't write yesterday.

•   A bias toward small, observable, reversible changes in a system that has 48 live integrations and real customers attached to each.

•   Authorised to work in the EU and based in or willing to relocate to Tallinn.

Nice to have

•   Prior work in EV, energy, smart grid, V2G, or e-mobility domains.

•   Experience with OCPP (chargers), Modbus, or other industrial and IoT protocols.

•   Familiarity with AWS Cognito as an identity provider beyond basic usage.

•   Experience operating multi-region services and dealing with geolocation-sensitive vendors.

•   Open-source contributions to the Go ecosystem or to public OEM-API clients.

What success looks like

First 3 months: Comfortable shipping changes across at least two existing integrations. On-call ready, able to triage and mitigate a typical connector incident without escalation. First small architectural improvement landed.

6 months: Delivered at least one new OEM integration end to end, or led a substantial reliability initiative (token refresh, rate-limit handling, credential rotation). Trusted to make build, defer, or deprecate calls on individual brands.

12 months: The integration layer is measurably more reliable, more uniform across brands, and faster to add new integrations to than it was on day one. New engineers can ship their first integration against a clear pattern that you defined.

Tech stack

Go, Kafka, gRPC, AWS (ECS, Lambda, KMS, Secrets Manager, Cognito, CloudWatch), Terraform, GitLab CI, Prometheus, OpenTelemetry.

Why Gridio

•   Real infrastructure connecting thousands of EVs to European energy markets.

•   Small team (around 12 people). Decisions are made fast and your work has direct impact.

•   Major utility partners across 8+ European markets.

•   Estonian company, English-speaking team, Tallinn-based with hybrid flexibility.

How to apply

Send a CV and a short note to [email protected] explaining why you are excited by the role and what makes you potentially great at it.