Zerodha is a name that resonates with millions of investors across India—it facilitates around 20% of all stock market transactions in the country and is renowned not only for its market presence but also for the ingenious technology that powers its operations. In this post, we take an outsider’s deep dive into Zerodha’s tech stack, exploring how its mix of open‑source tools, self‑hosted solutions, and first‑principles engineering has become a cornerstone of its success.
“Zerodha’s approach isn’t about following every new trend; it’s about solving real‑world problems with the right tools. Their journey is a masterclass in building resilient, scalable systems while keeping a keen eye on cost efficiency.”
Setting the Stage: The Stakes of Fintech Innovation
Imagine a company that processes millions of transactions every day in one of the most regulated industries in the world. Zerodha not only meets that challenge head‑on but has also dramatically increased its profitability over the past few years—all thanks, in part, to a strategic focus on building its own, self‑hosted technology infrastructure.
An insider once explained in a presentation in Hyderabad that the decision to self‑host open‑source software has saved Zerodha tens of millions of dollars. To put that into perspective, while a crypto exchange like Coinbase might shell out over $65 million a quarter for observability alone, Zerodha’s cost‑efficient approach has allowed it to reinvest savings into innovation and further growth.
The Philosophy: First‑Principles, Self‑Reliance, and Agility
At the heart of Zerodha’s tech strategy is a commitment to first‑principles thinking. Every tool, every language, and every piece of infrastructure is chosen after rigorous prototyping and careful evaluation of the real problem at hand. This results in:
- Cost Efficiency & Flexibility:
Rather than locking into expensive managed services, Zerodha runs critical databases (like PostgreSQL and, more recently, ClickHouse) on bare‑bones EC2 instances. This approach not only slashes operating costs but also enables seamless technology swaps when better alternatives emerge. - Regulatory Agility:
In fintech, regulatory changes can be sudden and far‑reaching. By maintaining complete control over its infrastructure, Zerodha can implement urgent changes swiftly without being held hostage by vendor roadmaps. - Empowered Culture:
The decision to self‑host isn’t just technical—it shapes the entire organizational mindset. Engineers learn every nuance of the systems they build, fostering a “hacker culture” that prizes deep technical knowledge over superficial abstraction. This capacity for hands‑on learning drives innovation and operational excellence across the board.
Breaking Down the Stack: Tools and Technologies in Action
Backend Services
- Python:
Zerodha’s early days saw Python used extensively for automating processes—transforming laborious tasks (like manual CSV processing) into swift, efficient operations. Today, Python continues to serve as a key language for various backend services and data processing tasks. - Go (Golang):
As the demand for high‑throughput, low‑latency processing grew—especially for streaming live market tick data—Go emerged as the hero. Its built‑in concurrency capabilities enable it to manage thousands of simultaneous websocket connections, making it ideal for real‑time financial applications.
Mobile & Web Front‑Ends
- Dart & Flutter:
Zerodha took a bold risk by betting on Flutter when it was still in its infancy. The result? A unified, cross‑platform mobile app that slashes development overhead and ensures a consistent experience across Android and iOS. - Vue.js:
On the web front, Zerodha’s trading interfaces are built with Vue.js. This framework’s blend of simplicity and reactive performance makes it a perfect choice for delivering a responsive and user‑friendly experience.
Data Management and Analytics
- PostgreSQL & ClickHouse:
PostgreSQL is the backbone of Zerodha’s transactional data storage—a battle‑tested solution known for its reliability. As data volumes have soared, ClickHouse has been introduced to handle massive amounts of immutable financial data with remarkable efficiency, reducing storage needs and speeding up query responses. - Redis:
For caching and in‑memory data processing, Redis keeps the applications nimble and responsive even under heavy load. - Grafana & Victoria Metrics:
Instead of spending exorbitant amounts on SaaS observability tools like DataDog, Zerodha has built its own observability stack. Grafana, paired with Victoria Metrics, offers granular control and significant cost savings in monitoring the health and performance of their systems.
Messaging & Orchestration
- Kafka & NATS:
Messaging is the nervous system of a distributed platform. Kafka serves as the high‑throughput, centralized message bus that coordinates millions of events per second, while NATS provides a lightweight alternative for low‑latency internal communications. - HashiCorp Nomad & GitLab CI/CD:
For deployment orchestration, Zerodha opts for Nomad—a simpler, yet powerful tool that efficiently manages deployments across EC2 instances. The build and deployment process is streamlined using GitLab CI/CD, ensuring that every code change is rigorously tested before going live.
Self‑Hosted Open‑Source Arsenal
Zerodha’s commitment to self‑hosting extends across its entire toolset. Some notable mentions include:
- OS Ticket:
A rock‑solid support ticketing system (built in PHP) that has reliably served the company for over 12 years. - ERPNext & Frappe:
These tools manage back‑office operations and internal business processes, offering the flexibility that comes from avoiding vendor lock‑in. - Airflow & Listmonk:
Managing ETL workloads and handling high‑volume email dispatches (sometimes up to 10 million emails in a single day) is made possible with these self‑hosted solutions. - Discourse, Haraka, and Mattermost:
From powering community forums (such as the popular tradingqna forum) to handling high‑speed email delivery and self‑hosted analytics, these tools illustrate the breadth and depth of Zerodha’s open‑source approach. - NextCloud & Password Managers:
Ensuring secure cloud storage and robust password management further cements the self‑hosted advantage.
The Self‑Hosting Advantage: Freedom, Savings, and Future‑Readiness
The decision to self‑host has had profound impacts on both the technical and financial fronts:
- Massive Cost Savings:
With self‑hosted databases and observability tools, Zerodha saves tens of millions of dollars compared to the steep costs associated with managed services. For instance, managed observability alone could cost hundreds of millions at scale. - Vendor Independence & Flexibility:
Self‑hosting gives Zerodha the agility to switch technologies as needs evolve—yesterday it was PostgreSQL, tomorrow it might be ClickHouse. This freedom also eliminates the overhead of managing relationships with multiple external vendors. - Empowering a Hacker Culture:
When engineers are involved in every layer—from installing databases to optimizing performance—they gain a deep understanding of the systems. This “get-your-hands-dirty” approach not only fosters innovation but also shifts the organizational mindset towards continuous improvement. - Mitigating Regulatory Risks:
In the fintech arena, regulatory changes can be sudden and unforgiving. With full control over its infrastructure, Zerodha can rapidly implement necessary changes, keeping it ahead of compliance challenges.
Lessons for Aspiring Technologists and Startups
For those building technology in today’s fast‑paced world, Zerodha’s journey offers valuable lessons:
- Don’t Fear Complexity—Embrace It:
Instead of relying solely on managed services that hide complexity behind a simple interface, invest the time to learn how systems work at a fundamental level. The insights gained are invaluable. - Prioritize Flexibility and Control:
Build systems that are modular and can adapt to change. Whether it’s switching out a database or rearchitecting a messaging system, the ability to pivot is key. - Self‑Hosting Is Not a Maintenance Nightmare:
While many warn that self‑hosting is complex and risky, Zerodha’s experience shows that with the right approach, it is a powerful path to independence and cost efficiency. For every dollar spent on managed services, there’s an opportunity to learn, innovate, and save substantially in the long run.
Conclusion
Zerodha’s tech stack is a masterclass in balancing innovation with practicality. By leveraging a blend of modern programming languages, robust open‑source tools, and a deep commitment to self‑hosting, Zerodha has built a system that is not only scalable and resilient but also incredibly cost‑efficient.
For anyone interested in the intersection of fintech, technology, and self‑reliance, Zerodha’s journey offers a clear message: build smart, stay agile, and never stop questioning if there’s a better way.
Explore the complete, detailed list of tools and technologies on the Zerodha Tech Stack page,
