Working at Mercury in 2026: The Fintech That Bet Everything on Haskell

Most fintechs start with Rails. Maybe Python. If they're feeling ambitious, Go or Rust. Mercury went a different direction entirely: they built their banking platform — every API endpoint, every transaction processor, every compliance check — in Haskell. Not as a side experiment. Not for one microservice. The entire backend. Millions of lines of production Haskell processing $248 billion in transaction volume in 2025.

This is the kind of engineering decision that either makes you lean forward in your chair or makes you close the browser tab. If you're still reading, Mercury might be your kind of company. Founded in 2019 by Immad Akhund and Jason Zhang, Mercury has grown from a scrappy startup banking alternative into the financial platform used by over 200,000 startups — backed by a $300 million Series C from Sequoia Capital and now in the process of obtaining a national bank charter from the OCC.

We analyzed employee reviews, engineering blog posts, and community sentiment to give you an honest picture of what it's actually like to work at Mercury in 2026. Whether you're evaluating an offer, preparing for an interview, or just curious about what a Haskell-at-scale engineering culture looks like in practice, here's what you need to know.

Mercury at a Glance

The Haskell Bet: Mercury's Defining Engineering Decision

Let's start with the elephant in the room, because it's the most interesting thing about Mercury as an engineering organization. When Immad Akhund and Jason Zhang founded Mercury in 2019, they made a decision that most CTOs would consider career-ending: they chose Haskell as their primary backend language for a banking platform.

The reasoning is straightforward once you understand what Mercury actually does. This is a company that moves money. Real money. Billions of dollars. When your transaction processor has a bug, it's not a broken button or a misaligned div — it's someone's payroll failing, or a wire transfer going to the wrong account, or a compliance violation that could result in regulatory action. In that context, Haskell's famously strict type system isn't academic indulgence. It's a risk management strategy.

Haskell's type system catches entire categories of bugs at compile time that would slip through in Ruby, Python, or even Go. Null pointer exceptions, type mismatches, improper state transitions — the compiler rejects them before the code ever runs. For a banking platform processing hundreds of billions in volume, that compile-time safety net translates directly into fewer production incidents and faster development velocity once engineers are up to speed on the language.

The trade-off is real, though. Haskell has a smaller talent pool than practically any mainstream language. Mercury can't just hire any experienced backend engineer — they need people who either already know Haskell or are motivated enough to learn it. This acts as a natural filter: Mercury's engineering team tends to attract people who are genuinely curious about programming languages, who care about correctness, and who are willing to climb a steep learning curve for long-term benefits. The result is unusually high talent density.

Tech Stack

The backend is exclusively Haskell — one of the largest production Haskell codebases in the world. The frontend is React, with Swift and Kotlin powering the mobile applications. Nix handles build tooling and reproducible environments, which pairs well with Haskell's emphasis on determinism. Infrastructure runs on AWS. It's an opinionated stack, and that's the point: every technology choice reflects the same philosophy of correctness and reliability that drove the Haskell decision in the first place.

Culture & Mission: Banking for the Builders

Mercury's mission is to make banking work for startups. Traditional banks were built for large enterprises with dedicated finance teams. Mercury built something different: a banking platform that understands how startups actually operate. Treasury management, automated bookkeeping, bill pay, corporate cards, venture debt — all in one product, designed for founders who would rather be building than managing banking relationships.

Over 200,000 startups now use Mercury, and the company reached $650 million in annualized revenue in 2025. The $300 million Series C from Sequoia, combined with the ongoing process to obtain a national bank charter from the OCC, signals that Mercury is transitioning from fintech startup to genuine financial institution. For employees, this means the work has real weight — you're not building another SaaS dashboard, you're building infrastructure that companies depend on to make payroll and fund operations.

CEO Immad Akhund brings an unusual background to fintech. A Y Combinator alum and serial entrepreneur, he's built multiple companies across different domains. His leadership style, according to employee reviews, emphasizes product quality and engineering autonomy over process and hierarchy. With approximately 85% CEO approval on employee reviews, he's well-regarded internally — particularly for maintaining a product-first culture even as the company scales past 1,300 employees.

Mercury earned Great Place to Work certification, with 95% of employees surveyed saying it's a great place to work. That's a strong signal, especially for a company growing as rapidly as Mercury has been — scaling from 850 to 1,300 employees in a relatively short period without losing culture is one of the hardest things in startups, and the data suggests Mercury is managing it well so far.

Glassdoor Ratings Breakdown

Mercury's overall Glassdoor rating of 4.3 out of 5.0, based on 112 employee reviews, places it in the upper tier among the companies in our Culture Directory. It's ahead of peers like Ramp and Stripe (4.0), and comparable to companies like Anthropic (4.4) and Databricks (4.3). Here's how the sub-categories break down:

The 3.8 WLB score is the most telling number. It's not bad — it's solidly in the middle of the pack — but it reflects the reality of a high-growth fintech that's scaling rapidly while simultaneously pursuing a bank charter. There are periods of intensity, particularly around regulatory milestones and major product launches. Mercury is honest about this trade-off: you're building something that matters, and that sometimes means long weeks. If you need a strict 40-hour week with no exceptions, this may not be the right fit.

Compensation & Benefits

Mercury's compensation is competitive for a growth-stage fintech. Total compensation for software engineers ranges from approximately $138K at IC1 (early career) to $300K+ at IC4, with a median around $214K. Senior and staff-level roles can reach up to $370K total comp. The equity component is particularly meaningful given Mercury's trajectory — $300M Series C from Sequoia, $650M annualized revenue, and a national bank charter application all point to significant future value.

For context, Mercury's comp is in line with well-funded fintech peers like Ramp and slightly below frontier AI companies like Anthropic or OpenAI, which offer $300K–$550K+ for senior engineers. But the equity upside at Mercury's current stage — post-Series C but pre-IPO — could close that gap significantly depending on how the bank charter process and continued revenue growth play out.

Benefits are comprehensive and reflect the company's startup-banking DNA: competitive healthcare, generous parental leave, and a genuine investment in professional development. The remote-friendly model means compensation is available to engineers outside the Bay Area, though there may be location-based adjustments.

What Employees Actually Say

We analyzed recurring themes across Mercury's employee reviews. Here's what stands out on both sides.

What employees love

The theme is consistent: Mercury attracts people who care about building a great product. The product-first mindset isn't just marketing — employees consistently cite it as one of the defining characteristics of the culture. Engineers have real input into product direction, design is taken seriously, and the Haskell codebase (love it or hate it) forces a level of thoughtfulness about code quality that permeates the engineering organization.

What could be better

The cons are classic growth-stage complaints, and they're the honest kind. Mercury is a company that's scaled from 850 to 1,300 employees in a short window while simultaneously building financial infrastructure, pursuing a bank charter, and expanding its product suite. Some organizational friction is inevitable. The question for candidates is whether you see ambiguity as an obstacle or an opportunity — the many-hats culture means there's room to define your role and have outsized impact, but you need to be comfortable with things not being fully figured out yet.

Who Thrives at Mercury

Based on the culture signals, employee reviews, and the engineering stack, here's who tends to do well at Mercury:

• Engineers who love programming languages. If you're the kind of developer who has opinions about type systems, who reads PL research papers for fun, or who's been looking for a reason to write Haskell professionally, Mercury is one of the only places in fintech where that passion is directly useful. You don't need to know Haskell coming in — but you need to be genuinely excited about learning it.
• Product-minded builders. Mercury's product-first culture rewards engineers who think beyond the code. If you care about why you're building something, not just how, and you want your work to directly impact 200,000+ startups, this is a strong fit.
• People who thrive in ambiguity. At ~1,300 employees with a many-hats culture, Mercury still has that "figure it out" energy. Processes are being built in real time. If you need a perfectly documented org chart and well-defined career ladder before you start, you'll be frustrated. If you see gaps as opportunities, you'll love it.
• Self-starters with high agency. The autonomy is real, but so is the expectation. Nobody is going to micromanage your day or tell you exactly what to build. You're expected to identify problems, propose solutions, and ship them — with support but without hand-holding.
• People who care about fintech's actual impact. Mercury isn't building another social app. When you ship a feature, it helps real founders make payroll, manage cash flow, and keep their companies alive. If that kind of tangible product impact motivates you, the mission resonance here is strong.

Mercury is not ideal for people who want a predictable, well-established big-company environment, or for engineers who prefer mainstream tech stacks and would rather not learn Haskell. The 3.8 WLB score means this is not a coast-and-collect job — there are genuine periods of intensity. If work-life balance is your top priority, consider companies like Notion, Linear, or HubSpot instead.