---
title: 'Senior/Staff Software Engineer, AI at Fonoa'
canonical: 'https://feeny.ai/job/senior-staff-software-engineer-ai-fonoa-london-rfq0664gsnyx'
type: 'job'
last_seen: '2026-09-07'
---

# Senior/Staff Software Engineer, AI at Fonoa

- **Company:** Fonoa
- **Location:** London, United Kingdom
- **Employment:** full-time
- **Work type:** hybrid
- **Posted:** 2026-05-08
- **Last confirmed live:** 2026-09-07
- **Apply:** https://jobs.ashbyhq.com/fonoa/d4683312-5a24-491d-9d0a-6f25c51f910c

## Job description

## ABOUT ENGINEERING AT FONOA

Engineering is central to how we build the business. We focus on solving real customer problems, not just shipping features. We work in small, high-trust teams, with full ownership across the lifecycle, from design to production and beyond.

We value:

- Ownership – engineers own what they build end-to-end
- Simplicity – we break down complex problems into clear solutions
- Thinking Big - we innovate with modern technologies (LLMs, AI Agents, etc.) to solve meaningful problems
- Quality – scalable, maintainable systems are non-negotiable
- Speed & iteration – we ship fast, learn, and improve continuously
- Collaboration – we win as a team, not as individuals

## POSITION OVERVIEW

As Fonoa continues to evolve its product capabilities, we are looking for a Senior or Staff Software Engineer to help us build AI-powered experiences that feel deeply integrated into the product, not layered on top of it.

This is not a role focused on experiments disconnected from production. You will work on real customer-facing systems, building intelligent workflows, natural language interfaces, and agent-driven experiences that make complex problems simpler for our users and internal teams.

You’ll work closely with engineering, product, and design to prototype, iterate, and scale new AI capabilities across the platform. This includes everything from designing backend systems that power AI workflows to shaping model behaviour, evaluation pipelines, and agent orchestration.

We are still early in this journey, which means this role requires someone who is comfortable operating in ambiguity, experimenting quickly, and helping define how AI is applied across products and workflows. We are looking for engineers who combine strong product instincts with deep technical understanding, and who are excited about building practical AI systems that deliver real value.

This is a highly collaborative, hands-on role for someone who enjoys owning problems end-to-end, moving quickly, and building systems that balance product experience, reliability, scalability, and long-term maintainability.

## WHAT YOU WILL DO

- Build AI-powered product features that feel native, fast, and intuitive to use
- Partner closely with product and design to prototype and iterate on intelligent workflows and user interactions
- Design backend services powering natural language interfaces, smart suggestions, and agentic systems
- Optimize prompts, shape model behaviour, and improve evaluation pipelines
- Build and evolve internal and external agent platforms
- Enable both technical and non-technical teams to leverage AI more effectively
- Continuously experiment, iterate, and improve AI systems in production

## WHAT WE’RE LOOKING FOR

- 5+ years building customer-facing products at a high-quality software company
- Strong track record of delivering complex, end-to-end product features with visible impact
- Ability to shape problems and drive solutions independently with high ownership
- Deep understanding of LLMs, prompt engineering, agent frameworks, and AI safety/security practices
- Experience with RAG architectures and model evaluation
- Strong product and engineering instincts, with the ability to balance speed, quality, and pragmatism
- Comfortable operating in fast-moving, ambiguous environments
- Proven ability to experiment and deliver in an evolving technology landscape

## API DOCUMENTATION

For engineers, API design and structure are an important part of evaluating a role. You can explore our API and how we build products here: https://docs.fonoa.com/

## TECH STACK

We use these technologies today, but we don’t hire for specific tools. We care about engineers who can understand problems, make good technical decisions, and choose the right tools for the job.

- Backend: Node.js, Go
- Frontend: React, TypeScript
- Infrastructure: GCP, k8s, Terraform, Postgres

Note: If you don’t think you have the full experience we’re looking for, but you could be a fit and are willing to learn, do apply anyway! We are building a diverse and inclusive team.

As part of the recruitment process at Fonoa, we process your personal data in accordance with our Privacy Notice for Job Applicants https://www.fonoa.com/legal/privacy-notice-job-applicants. This notice explains how and why your data is collected and used, and how you can contact us if you have any concerns.

## About Fonoa

## Company Overview
- **One-liner**: Fonoa provides an AI-driven global tax automation platform that handles determination, e-invoicing, return filing, and tax ID validation for digital businesses.
- **Entity Type**: Private (most recent funding round: $110M in May 2026, total funding $195M)
- **Headquarters**: Dublin, Ireland
- **Founded**: 2019
- **Founders**: Filip Sturman (Co-founder & COO) and other co-founders formerly at Uber (names not publicly disclosed)

## Core Business
- **Primary industry/industries**: Tax compliance automation, financial technology (FinTech)
- **Target customers**: B2B – multinational digital platforms, marketplaces, SaaS businesses, and enterprises. Examples include Uber, Zoom, Booking, and Remote.com.
- **Mission or purpose statement**: “Real-time tax compliance for innovators” – to remove tax complexity so businesses can scale globally.

## Products & Services
- **Tax Engine (API)**: Deterministic tax calculation (VAT, GST, Sales Tax) across 190+ jurisdictions with sub-200ms response time. ([fonoa.com](https://www.fonoa.com/))
- **E-Invoicing**: Compliant e-invoicing with accredited government connections, ultra-low rejection rates. Powers invoicing for 1M+ sellers on leading marketplaces. ([fonoa.com](https://www.fonoa.com/))
- **Tax Return Filing**: Automated multi-country return filing with full lineage from return box to source transaction. ([fonoa.com](https://www.fonoa.com/))
- **Tax ID Validation**: Real-time validation of tax IDs in 120+ countries, with fuzzy name matching. ([fonoa.com](https://www.fonoa.com/))
- **Tax Knowledge AI**: A living global tax intelligence layer that answers complex questions with cited sources. ([fonoa.com](https://www.fonoa.com/))
- **Audit Readiness Tool**: Compresses audit readiness from weeks to minutes by providing instant access to all tax data. ([fonoa.com](https://www.fonoa.com/))

## Market Standing
- **Valuation**: Not publicly disclosed
- **Key Metric**: Total Funding – $195M (including $110M raised May 2026, which also funded the acquisition of PwC’s Global Indirect Tax Compliance platform) ([cbinsights.com](https://www.cbinsights.com/company/fonoa))
- **Notable Investors**: Index Ventures (Seed), OMERS Ventures (Series A), Coatue (Series B). Lead investor in May 2026 round not specified in search results. ([linkedin.com](https://www.linkedin.com/company/fonoa))
- **Growth Signals**:
  - 500M+ transactions processed annually.
  - Customer retention rate 97% (100% of customers who started 2025 renewed).
  - Headcount growth of +51.3% YoY (184 employees, up 79 in the last year).
  - Named to Sifted’s B2B SaaS Rising 100 for four consecutive years (2023–2026). ([fonoa.com](https://www.fonoa.com/company/about))

## Competitive Advantages
- **Single platform for the entire indirect tax lifecycle** – reduces integration complexity vs. stitching together multiple point solutions.
- **AI agents automate compliance workflows** while humans supervise, enabling audit readiness in minutes.
- **Deep government connections** for e-invoicing with near-zero rejection rates.
- **Uber pedigree** – founders built the platform based on firsthand experience scaling a global digital business.
- **Fast integration** – typical go-live in weeks or days, not months.

## Strategic Focus
- **AI-first tax platform**: Launched AI agents to autonomously execute compliance workflows, with human oversight. ([fonoa.com](https://www.fonoa.com/))
- **Post-acquisition integration**: Absorbing PwC’s global indirect tax compliance platform to expand reach and capabilities. ([fonoa.com](https://www.fonoa.com/company/about))
- **Global expansion**: Covers 190+ jurisdictions and continues to add new country support.
- **Product-led growth**: Prioritizing developer experience and API-first design to embed tax intelligence into customer products.

## Why Work Here
- **Culture & Mission**: Described as “the fastest-growing tech company in our space”; teams are encouraged to tackle complex global tax challenges with autonomy and collaboration. ([fonoa.com/company/careers](https://www.fonoa.com/company/careers))
- **Work Model**: Hybrid and remote opportunities available (depending on role); regular office meetups and team offsites. ([fonoa.com/company/careers](https://www.fonoa.com/company/careers))
- **Perks & Benefits**:
  - Competitive salary and equity stake.
  - 25 days paid time off (PTO).
  - Home office allowance for remote setup.
  - Bi-weekly team lunches.
  - Annual all-company trip (“FUNoa”) for learning and bonding.
- **Engineering & Growth**: Strong focus on engineering quality (Senior/Staff roles open in AI, frontend, data). 24% of employees are in technical departments. ([linkedin.com](https://www.linkedin.com/company/fonoa))
- **Diversity**: Operates across 18 countries with distributed teams, offering international exposure.

## Sources
1. [fonoa.com](https://www.fonoa.com/) – Product descriptions, mission, customer logos, company numbers.
2. [fonoa.com/company/about](https://www.fonoa.com/company/about) – Founding story, funding news ($110M raise + PwC acquisition), Sifted recognition.
3. [fonoa.com/company/careers](https://www.fonoa.com/company/careers) – Benefits, culture, hiring process, hybrid/remote policy.
4. [linkedin.com](https://www.linkedin.com/company/fonoa) – Employee count, revenue, funding, headcount growth, founders, exec team.
5. [cbinsights.com](https://www.cbinsights.com/company/fonoa) – Total funding amount ($195M), latest round details.

## Other roles at Fonoa

- [Junior Tax Content Analyst](https://feeny.ai/job/junior-tax-content-analyst-fonoa-zagreb-7rtfetjsncqm) — Zagreb, Croatia
- [Solutions Architect- Indirect Tax](https://feeny.ai/job/solutions-architect-indirect-tax-fonoa-new-york-s548kp6hhz9y) — New York, NY
- [Solutions Consultant, (Indirect Tax)](https://feeny.ai/job/solutions-consultant-indirect-tax-fonoa-new-york-dzfngb7jwbvj) — New York, NY
- [Senior Software Engineer](https://feeny.ai/job/senior-software-engineer-fonoa-zagreb-56ca7b0s69m5) — Zagreb, Croatia
- [Procurement Manager](https://feeny.ai/job/procurement-manager-fonoa-zagreb-npyjcksx0b9x) — Zagreb, Croatia
- [Regional Sales Director](https://feeny.ai/job/regional-sales-director-fonoa-london-g7169nv4bdqy) — London, United Kingdom
- [Sales Development Representative](https://feeny.ai/job/sales-development-representative-fonoa-new-york-aqtp3rtpvznh) — New York, NY
- [Sales Development Representative](https://feeny.ai/job/sales-development-representative-fonoa-london-0a25z0w2q70j) — London, United Kingdom
- [Senior User Researcher](https://feeny.ai/job/senior-user-researcher-fonoa-london-47y4pyecpxxn) — London, United Kingdom
- [Staff Product Designer](https://feeny.ai/job/staff-product-designer-fonoa-london-v7skvrgp6vk4) — London, United Kingdom