# Backend Engineer [Viktor](https://gurify.com/jobs?q=Viktor) · Warsaw · Posted 2 months ago [Backend](https://gurify.com/jobs/backend) [Apply on the original posting → (opens in a new tab)](https://jobs.ashbyhq.com/viktor/143f3943-33ab-4614-87b8-8435517d8830) ## Job description ### THE SHORT VERSION You make everything the agent runs on solid: the integrations it reaches through, the gateway that turns them into functions it can call, the sandboxes it runs in, and the data underneath. You've built and operated real backend systems in production and have scars from how they break. You may never have shipped an LLM feature, and that's fine. If you haven't run systems in production, this isn't the role. ### THE HARD PART Viktor reaches into 3,200+ integrations for 56,000+ workspaces, 5M+ tool calls a day, on real customer data. Every integration that quietly misbehaves is a task the agent gets wrong. We're building a harness ready for AGI-level models: an agent that explores what a company runs on and automates it on its own. That bet lives or dies on the backend underneath. The gateway, sandboxes, and data every task runs through have to be fast, solid, and never the reason the agent got it wrong. ### WHAT YOU'LL ACTUALLY DO - Own integration quality end to end: catch issues before customers do, fix them, and make sure they can't recur. - Build the tool gateway: turn every connected API and MCP into a clean Python SDK the agent composes, with routing, auth, rate limits, and reliability. - Run the sandboxes: a persistent Linux environment per workspace, isolated, secured, autoscaled, and cheap per task. - Own the data layer: state and persistence across 56,000+ multi-tenant workspaces, durable and fast. - Whatever needs building. Small team, large surface. ### WHO YOU ARE - You design distributed systems for scale and reliability, and have operated them in production through the breakage. - You know sandboxing and OS-level isolation cold: containers, Linux internals, running untrusted code safely. - You've wrangled real integration plumbing: OAuth, webhooks, rate limits, and third-party APIs that lie. - You think in multi-tenancy, durability, and cost per request, and design for failure by default. - Security and blast radius are instincts you bring to every design, especially when the thing executes model-written code. - You build with AI by default, because that's how the team moves. - You may never have shipped an LLM feature, and that's fine. This is a systems role. ### WHY THIS ROLE IS DIFFERENT - No layers. You work directly with both founders, and decisions get made in the room, not in a Linear ticket. - The backend is the ceiling. Every integration you make reliable and every sandbox you make cheaper raises what the whole agent can do. - You're building the backend of a frontier harness: the layer that decides how much of the model's intelligence turns into real work. ### EVEN BETTER IF - You've worked on infrastructure, platform, or developer-tools teams where reliability was the product. - You've built sandboxing, code-execution, or multi-tenant systems before. - You're at home in agentic engineering workflows, spec to production. - You've contributed to the open-source infrastructure the world runs on. - You've founded something or been an early-stage builder. ### TECH Python. No agent framework and no container orchestration layer: Python services, persistent Linux sandboxes per workspace, Modal for infrastructure. You'll live in OAuth and webhooks, the tool gateway, and multi-tenant data. You don't need all of it coming in, but you need to learn fast. ### HOW WE WORK Small team, high trust, low process. Decisions are made by owners, not committees. You will ship your first week. You will talk to users your first day. We don't do alignment meetings or stakeholder syncs. We build things, see if they work, and iterate. ### WHY VIKTOR We're one of the fastest-growing companies in the world. The product works. The market is pulling. This is a rare window: everyone here owns something real. Not a task. A surface of the company that customers depend on. That doesn't last forever. Right now, it's still true. ### COMPENSATION Top-of-the-market salary and the kind of ownership that only exists at this stage. The best work happens when you're in the room. This role is Munich or Warsaw. **Live in Viktor’s hiring system.** Read from the company's own applicant tracking system, not reposted from a job board — so it's a real, open requisition rather than an ad that outlived the role. We remove it as soon as it disappears at source. ## More jobs like this - VO [Senior Backend Engineer, Poland (m/f/d)](https://gurify.com/job/senior-backend-engineer-poland-m-f-d-at-voize-94a90c21a75f) Voize · Warzaw, Poland · 4 days ago - LE [Backend Engineer - Reporting](https://gurify.com/job/backend-engineer-reporting-at-leovegasgroup-ee0d7c2f9ca3) Leovegasgroup · Warsaw, Poland · 3 days ago - ST [Copy of Backend Engineer - Golang](https://gurify.com/job/copy-of-backend-engineer-golang-at-sensor-tower-494b0d420926) Sensor Tower · Warsaw, Poland · 2 days ago - SS [FinTech Client #3 | Backend Engineer](https://gurify.com/job/fintech-client-3-backend-engineer-at-sd-solutions-64195d551dc2) SD Solutions · Warsaw, Poland · 3 weeks ago - HY [Senior Backend Engineer](https://gurify.com/job/senior-backend-engineer-at-hyperexponential-4ed0cd5f7581) Hyperexponential · Warsaw (hybrid) · 3 days ago - MO [Senior Backend Engineer (f/m/d)](https://gurify.com/job/senior-backend-engineer-f-m-d-at-moss-8ef331c5f6bf) Moss · Warsaw · 5 weeks ago ```json {"@context":"https://schema.org/","@type":"JobPosting","title":"Backend Engineer","description":"\u003Ch3\u003ETHE SHORT VERSION\u003C/h3\u003E\u003Cp\u003EYou make everything the agent runs on solid: the integrations it reaches through, the gateway that turns them into functions it can call, the sandboxes it runs in, and the data underneath. You\u0026#39;ve built and operated real backend systems in production and have scars from how they break.\u003C/p\u003E\u003Cp\u003EYou may never have shipped an LLM feature, and that\u0026#39;s fine. If you haven\u0026#39;t run systems in production, this isn\u0026#39;t the role.\u003C/p\u003E\u003Ch3\u003ETHE HARD PART\u003C/h3\u003E\u003Cp\u003EViktor reaches into 3,200\u002B integrations for 56,000\u002B workspaces, 5M\u002B tool calls a day, on real customer data. Every integration that quietly misbehaves is a task the agent gets wrong.\u003C/p\u003E\u003Cp\u003EWe\u0026#39;re building a harness ready for AGI-level models: an agent that explores what a company runs on and automates it on its own. That bet lives or dies on the backend underneath. The gateway, sandboxes, and data every task runs through have to be fast, solid, and never the reason the agent got it wrong.\u003C/p\u003E\u003Ch3\u003EWHAT YOU\u0026#39;LL ACTUALLY DO\u003C/h3\u003E\u003Cul\u003E\u003Cli\u003EOwn integration quality end to end: catch issues before customers do, fix them, and make sure they can\u0026#39;t recur.\u003C/li\u003E\u003C/ul\u003E\u003Cul\u003E\u003Cli\u003EBuild the tool gateway: turn every connected API and MCP into a clean Python SDK the agent composes, with routing, auth, rate limits, and reliability.\u003C/li\u003E\u003C/ul\u003E\u003Cul\u003E\u003Cli\u003ERun the sandboxes: a persistent Linux environment per workspace, isolated, secured, autoscaled, and cheap per task.\u003C/li\u003E\u003C/ul\u003E\u003Cul\u003E\u003Cli\u003EOwn the data layer: state and persistence across 56,000\u002B multi-tenant workspaces, durable and fast.\u003C/li\u003E\u003C/ul\u003E\u003Cul\u003E\u003Cli\u003EWhatever needs building. Small team, large surface.\u003C/li\u003E\u003C/ul\u003E\u003Ch3\u003EWHO YOU ARE\u003C/h3\u003E\u003Cul\u003E\u003Cli\u003EYou design distributed systems for scale and reliability, and have operated them in production through the breakage.\u003C/li\u003E\u003C/ul\u003E\u003Cul\u003E\u003Cli\u003EYou know sandboxing and OS-level isolation cold: containers, Linux internals, running untrusted code safely.\u003C/li\u003E\u003C/ul\u003E\u003Cul\u003E\u003Cli\u003EYou\u0026#39;ve wrangled real integration plumbing: OAuth, webhooks, rate limits, and third-party APIs that lie.\u003C/li\u003E\u003C/ul\u003E\u003Cul\u003E\u003Cli\u003EYou think in multi-tenancy, durability, and cost per request, and design for failure by default.\u003C/li\u003E\u003C/ul\u003E\u003Cul\u003E\u003Cli\u003ESecurity and blast radius are instincts you bring to every design, especially when the thing executes model-written code.\u003C/li\u003E\u003C/ul\u003E\u003Cul\u003E\u003Cli\u003EYou build with AI by default, because that\u0026#39;s how the team moves.\u003C/li\u003E\u003C/ul\u003E\u003Cul\u003E\u003Cli\u003EYou may never have shipped an LLM feature, and that\u0026#39;s fine. This is a systems role.\u003C/li\u003E\u003C/ul\u003E\u003Ch3\u003EWHY THIS ROLE IS DIFFERENT\u003C/h3\u003E\u003Cul\u003E\u003Cli\u003ENo layers. You work directly with both founders, and decisions get made in the room, not in a Linear ticket.\u003C/li\u003E\u003C/ul\u003E\u003Cul\u003E\u003Cli\u003EThe backend is the ceiling. Every integration you make reliable and every sandbox you make cheaper raises what the whole agent can do.\u003C/li\u003E\u003C/ul\u003E\u003Cul\u003E\u003Cli\u003EYou\u0026#39;re building the backend of a frontier harness: the layer that decides how much of the model\u0026#39;s intelligence turns into real work.\u003C/li\u003E\u003C/ul\u003E\u003Ch3\u003EEVEN BETTER IF\u003C/h3\u003E\u003Cul\u003E\u003Cli\u003EYou\u0026#39;ve worked on infrastructure, platform, or developer-tools teams where reliability was the product.\u003C/li\u003E\u003C/ul\u003E\u003Cul\u003E\u003Cli\u003EYou\u0026#39;ve built sandboxing, code-execution, or multi-tenant systems before.\u003C/li\u003E\u003C/ul\u003E\u003Cul\u003E\u003Cli\u003EYou\u0026#39;re at home in agentic engineering workflows, spec to production.\u003C/li\u003E\u003C/ul\u003E\u003Cul\u003E\u003Cli\u003EYou\u0026#39;ve contributed to the open-source infrastructure the world runs on.\u003C/li\u003E\u003C/ul\u003E\u003Cul\u003E\u003Cli\u003EYou\u0026#39;ve founded something or been an early-stage builder.\u003C/li\u003E\u003C/ul\u003E\u003Ch3\u003ETECH\u003C/h3\u003E\u003Cp\u003EPython. No agent framework and no container orchestration layer: Python services, persistent Linux sandboxes per workspace, Modal for infrastructure. You\u0026#39;ll live in OAuth and webhooks, the tool gateway, and multi-tenant data. You don\u0026#39;t need all of it coming in, but you need to learn fast.\u003C/p\u003E\u003Ch3\u003EHOW WE WORK\u003C/h3\u003E\u003Cp\u003ESmall team, high trust, low process. Decisions are made by owners, not committees. You will ship your first week. You will talk to users your first day.\u003C/p\u003E\u003Cp\u003EWe don\u0026#39;t do alignment meetings or stakeholder syncs. We build things, see if they work, and iterate.\u003C/p\u003E\u003Ch3\u003EWHY VIKTOR\u003C/h3\u003E\u003Cp\u003EWe\u0026#39;re one of the fastest-growing companies in the world. The product works. The market is pulling.\u003C/p\u003E\u003Cp\u003EThis is a rare window: everyone here owns something real. Not a task. A surface of the company that customers depend on. That doesn\u0026#39;t last forever. Right now, it\u0026#39;s still true.\u003C/p\u003E\u003Ch3\u003ECOMPENSATION\u003C/h3\u003E\u003Cp\u003ETop-of-the-market salary and the kind of ownership that only exists at this stage.\u003C/p\u003E\u003Cp\u003EThe best work happens when you\u0026#39;re in the room. 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