Senior Back End Engineer (Integrations)

About Abacum Abacum is the leading Business Planning solution for finance teams to drive performance. By automating reporting, enabling collaboration, and simplifying planning and forecasting, we help finance teams shift from number crunching to driving strategic decisions. Founded in 2020 by two former CFOs, we’ve grown into a global team of 100+ people across 30+ nationalities. Headquartered in New York, we have offices in Toronto and Barcelona. We’re trusted by industry leaders such as Dish Networks, Strava, BetterUp, Kajabi, JG Wentworth, Abridge, Cortex, and hundreds more. We have raised over $100m, closing in June 2025 our $60M Series B, led by Scale Venture Partners, with the strong participation of Cathay Innovation, Y Combinator, Atomico, Creandum, and angel operators from Adyen, Zapier, and Twitch. Our mission is ambitious and we can’t do it alone - join Abacum as we build the future of Business Planning! We are looking for... … talented engineers who possess infinite curiosity to solve complex problems not existing in the market (multi dimensional real time calculations engine), are excited to become part of our early story and help create groundbreaking technology that truly improves how finance teams work and collaborate. Creating an amazing opportunity to code in an extremely agile environment, with a direct long-term impact on our product and users. Our ideal candidate has a strong sense of ownership in their work, is willing to learn quickly, committed to shaping our technical design and engineering culture. Being a Software Engineer at Abacum means... - Collaborate closely with engineers, product designers, and product to perform experiments and test new ideas - Build performant, design-centric, reusable and usable interfaces that solve complex needs. Such as customisation possibilities for our users, complex data visualisations (graphs, charts, etc...), delightful components that provide the best platform experience - Drive user defined data modeling and performance, providing the user with customization possibilities through reusable building blocks: models, variables, formulas, … - Take operational responsibility for the components that you write - Work in an environment that supports your individual growth by providing you with challenging tasks and projects to solve and the freedom to acquire new skills in hack time - Work with product and our operations team to incorporate customer feedback in order to constantly improve our product - Scale our complex data and calculations platform for a fast growing number, size and complexity of clients What You’ll Do as a Senior Back End in the integrations team: - Move fluently across multiple programming languages and ecosystems beyond our core stack (not limited to Python or Django) to read, adapt, and extend integration-specific code such as ERP scripting frameworks (e.g. SuiteScript), native app extensions for accounting and finance platforms, and third-party vendor SDKs. - Work confidently with a wide range of authentication and identity flows, including OAuth 2.0 / OIDC, SSO providers (Microsoft Entra ID, Okta, Google Workspace), SAML, and service-to-service authentication. Comfortable managing different token types (access, refresh, JWT, API keys), handling token lifecycles, and applying secure communication protocols (TLS/HTTPS, signed requests, secret management) across all integrations. - Lead the design and development of Abacum's integrations platform for ingesting, normalizing, and annotating business data. - Build and scale bidirectional integrations with billing, accounting, ERP, commerce, and HRIS platforms. - Architect low-code/no-code tools (e.g. connector builder, declarative DSLs, LLM-assisted workflows), and choose between integration strategies (unified API, in-house, contractors) to accelerate integration development and maintenance. - Ensure integrations are secure, resilient, and performant at scale, supporting high-volume financial and tran