How Nubank validates APIs 8x faster to serve 131 million customers

Before July 2025, enabling a new Slack integration project meant starting from scratch. To validate an integration, the Internal Development team first had to write custom-built scripts to connect APIs, retrieve the required data and build a proof of concept (PoC). It was the same process used to build tools that manage Slack sessions and guest user access.

It was a slow and difficult workflow to scale and often pushed discovery outlines out by days. For a simple tool, it would take about four hours to produce an initial test script. While for a more intermediate tool, it would take around two days. Instead of moving quickly from discovery to validation, the team spent a considerable amount of time building one-off scripts just to prove an integration would work.

The workflow also created a collaboration bottleneck. Knowledge about how these integrations worked was held by a single team member on their machine. This made it difficult to share context, reuse work or scale discovery across the team as new projects came in.

Another challenge was that non-technical stakeholders needed to be able to trigger specific integrations manually and perform checks or remedial actions through APIs. There was no shared, safe interface which meant these stakeholders relied on the team which increased the support load.

The combined effect was that integrations took longer to deliver, and the value they were meant to bring to productivity, governance and operations arrived later than it should have.

In July 2025, the Internal Development team redesigned its integration workflow around the Postman API Platform, making it the starting point for every new integration. The goal was to deliver integrations at speed that would benefit the business.

The most impactful feature is Postman Flows which are used to model end-to-end scenarios to show how multiple APIs work together before a single line of code is committed. While collections are used to explore and validate individual APIs. Scripts are no longer the first step in API development.

For many simple and intermediate integrations, Flows replaced the need for a traditional scripted PoC.

Days of script work have been eliminated. Now, the HTTP sequence is reproduced in Postman or in a flow to check authentication, rate limits, and data handling first, before the build begins. The time saved is a productivity driver.

To keep everyone aligned, the team created a shared Postman workspace that serves as a single source of truth. Collections, environments, and Flows describing how tools integrate, now all live in one place. This has made the team's work reusable across the business.

Today, the entire team has full visibility into the history of tests and integrations. Knowledge is encoded in Postman which is reducing onboarding time and risk, while removing dependency on a single person to understand how integrations work.

To safely empower operations and other non-technical stakeholders, the team documented collections and Flows with clear naming and descriptions. Alongside this, guardrails were added on which requests can be run and how.

Non-technical users have structured handovers, including walkthroughs and simple playbooks, so they know exactly which requests to use for which jobs. There's now a controlled way to trigger specific actions, run checks, and interact with integrations, without touching scripts or code. They just have to run predefined requests in Postman to trigger integrations or retrieve data using Flows and collections. Now, non-technical users can act on their own work and their dependency has been removed.

For Nubank, Flows have enabled non-technical team members across operations to contribute to API integrations. That has removed software engineering bottlenecks and expanded both the speed and the scope of who can work with APIs. The result is a reduced ad-hoc support load, improved response times for operations, and manual processes that are now repeatable and auditable.

The time taken to validate integrations has been reduced from hours or days to minutes. Overall, Postman has made API validation time 8x quicker for all types of integrations ranging from simple to complex.

For simple integrations, it now only takes five minutes to validate APIs whereas previously it required four hours of scripting for the PoC. It's an estimated 48x improvement.

Whereas for intermediate integrations, the time taken to validate integrations has dropped from two days to 30 minutes, making them roughly 32x faster.

Consequently, integration projects can be planned with confidence. While the same level of effort results in a higher volume of integration work due to faster validation times.

Collaboration and resilience have also transformed. Moving from scripts on a single machine to a shared Postman workspace eliminated a single point of failure. Critical knowledge has been distributed across the entire team, they can now understand, maintain, and evolve integrations independently. Onboarding is faster too, as new team members can explore existing collections and Flows instead of having to reconstruct behavior from scratch.

Postman has scaled API integration work at Nubank into a capability the business can share improving productivity, scaling cross-team collaboration, while enhancing governance and operations.