Juspay and Cumbuca Open-Source a Developer Playground for Brazil's Open Finance

Brazilian fintech infrastructure took a step toward maturity this week as Juspay and Cumbuca released the Open Finance Playground, a free, open-source documentation and simulator stack designed to compress the multi-week onboarding curve that has slowed new entrants into Brazil's Open Finance ecosystem. The release targets a structural bottleneck in the world's largest open banking market: regulator-grade specifications that describe what compliant systems must do, but offer little practical guidance on how to

build them.

The Playground, hosted at juspay.io/open-finance, distills hundreds of pages of regulatory specifications into step-by-step implementation guides covering consent management, payment initiation, and the security stack of FAPI, mTLS, JWS, and Dynamic Client Registration. It is endorsed by INIT, the Brazilian association of Payment Transaction Initiators, of which Cumbuca is a co-founder.

Why does Brazil's Open Finance matter to global investors?

Brazil now operates the largest Open Finance ecosystem in the world by participation, a fact that has gone underappreciated outside Latin America. According to figures published alongside the Playground launch, more than 100 million customers are connected to the system, with 154 million active consents in circulation. Unique consents grew 143% between 2024 and 2025, and weekly inter-institutional communications now exceed 5 billion. Payment initiation volume reached R$15.3 billion in 2025, nearly five times the R$3.2 billion recorded in 2024.

For comparison, the United Kingdom, widely regarded as the open banking benchmark, has roughly 20% of its companies connected, while Brazil sits at 3%, suggesting the Brazilian ecosystem still has substantial room to expand on the institutional side even as consumer participation already outstrips most peers. Public awareness in Brazil reached 76.8% in the most recent measurement, with 37.1% of citizens having actively authorized data sharing.

What problem is the Playground actually solving?

The official documentation maintained by Open Finance Brasil is comprehensive and meets its regulatory remit. It is, however, organized as a specification rather than as a tutorial. Engineers entering the ecosystem have historically needed to cross-reference dozens of external RFCs and reverse-engineer implicit requirements before issuing their first compliant API call.

Juspay and Cumbuca built the Playground from internal engineering notes generated while implementing Open Finance flows in production. The documentation covers end-to-end API sequences, undocumented bank-specific behaviors that surface only at integration time, and the full consent lifecycle including renewals and revocations. A live simulator allows developers to inspect every API call behind a given user flow and trace the audit trail step by step.

How does this fit into the wider open banking trend?

Open banking has moved from regulatory compliance project to competitive infrastructure across multiple jurisdictions. The European Union is finalizing PSD3 and the Financial Data Access (FIDA) framework, the United States issued its CFPB Section 1033 personal financial data rule in 2024, and Saudi Arabia, India, and Australia have all advanced national frameworks. Developer experience, rather than regulation, is now the rate-limiting factor in most of these markets.

Initiatives such as the Open Finance Playground signal a shift familiar to anyone who watched cloud computing mature: once the standards stabilize, value migrates to the tooling layer that makes those standards usable. The fact that two commercial firms, one a global payments infrastructure provider operating in over 30 countries and the other a Banco Central do Brasil-authorized Payment Institution, have chosen to open-source their internal documentation suggests the competitive moat has moved from access to execution.

Who built it and why open source?

Juspay serves as primary maintainer and repository owner, contributing global payments engineering experience. Cumbuca, authorized as a Payment Institution by Brazil's Central Bank and a co-founder of INIT, contributes regulatory expertise and operational knowledge of the domestic ecosystem. The project is maintained on GitHub with public contribution guidelines covering issues, pull requests, and code samples in additional languages.

The decision to open-source mirrors a pattern seen in payments infrastructure more broadly: when integration friction depresses ecosystem growth, the marginal benefit of a shared toolchain outweighs the proprietary advantage of holding internal documentation private. Every fintech that ships faster on Open Finance is a potential counterparty, customer, or downstream user of paid infrastructure further up the stack.

Why This Matters to FinanceX Readers

Brazil's Open Finance numbers are no longer a regulatory curiosity, they are a live commercial system processing billions of communications weekly and accelerating in payment initiation volume.

For investors evaluating Latin American fintech exposure, infrastructure projects like the Open Finance Playground are leading indicators: they signal that the market has crossed from compliance phase to scale phase, and that the next round of entrants will have substantially lower technical onboarding costs than incumbents.

That changes the unit economics of new fintech formation in Brazil and merits attention from anyone underwriting the region.

By Koen Vanderhoydonk - FinanceX Magazine