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Fern is a stablecoin payments and currency conversion API that lets developers add onramps, offramps, FX and crypto exchange to their apps through one integration (Fern docs). In December 2025 it was acquired by Rain, a stablecoin payments and card infrastructure company (Fern).
An earlier version of this review described Fern as a decentralized, overcollateralized stablecoin protocol with its own governance token and DAO. That was not accurate. Fern does not issue a stablecoin or a token; it is a compliance-led payments API that moves money between fiat, stablecoins and crypto. This 2026 review is based on Fern’s own site and documentation and Rain’s acquisition announcement.
Key Takeaways
- Fern is a payments API for onramps, offramps, FX and crypto-to-crypto transfers, not a stablecoin issuer (Fern docs).
- Rain acquired Fern on December 2, 2025, and Fern’s routing engine, the Multiplex, is being integrated into Rain’s platform (Fern).
- Fern supports USDC, USDT, PYUSD and EURC on six networks: Ethereum, Arbitrum, Base, OP Mainnet, Polygon and Solana (Fern docs).
- Fern’s docs list multi-currency virtual accounts accepting fiat in 15+ currencies (Fern docs).
- Existing Fern customers keep their integrations and API keys during the move to combined Rain and Fern products.
What Is Fern?
Fern Money, LLC is a Delaware company whose homepage pitches “global money movements in record time” across fiat, stablecoins, cryptocurrencies and bank rails (Fern). It serves two audiences: developers, who can use its API to go live with compliant money movement within days, and businesses, which can use an onchain spending and savings account built for global teams.
Fern works with licensed liquidity providers and financial institutions and exposes them through one standardized API (Fern docs). Rain says Fern founder Pooja Shah previously led Filecoin and core product work at Protocol Labs and has joined Rain as Head of Product (Rain).
The Rain acquisition
Fern announced its acquisition by Rain on December 2, 2025. The partnership started with Fern using Rain for card capabilities, and the two teams decided to combine to offer wallets, payins and payouts, bridging, swaps and cards through a single API (Fern). Fern’s About page now describes the company as part of Rain, “the leader in stablecoin-powered payments and card programs” (Fern).
How Fern Works
Fern’s documentation lists five core pieces (Fern docs):
- Multiplex API: any-to-any conversion between supported crypto and fiat currencies.
- Wallets API: wallets provisioned for your users for onramping, offramping and deposits.
- Multi-currency virtual accounts: named accounts for business and individual customers to receive fiat.
- Compliance program: white-labelled KYC and KYB forms, with Fern’s compliance team reviewing applications.
- Developer experience: a dashboard, API keys for pre-production and production, and hands-on support.
The Multiplex
The Multiplex is the part Rain was most interested in. Rain describes it as a routing, orchestration and compliance engine made of four parts: standardized APIs to liquidity providers, banks and blockchains; a compliance engine that checks user permissions and transaction requirements; a layer of permissioned liquidity providers and bank partners; and a router that compares conversion paths and picks the best one (Rain).
Chains and currencies
Fern lists Ethereum, Arbitrum, Base, OP Mainnet and Polygon as live for USDC, USDT, PYUSD, EURC, ETH and ERC-20 tokens, and Solana as live for USDC, USDT, PYUSD, EURC, PAXG and WBTC (Fern docs). Solana support launched in September 2025 (Fern changelog).
On the fiat side, Fern connects to local payment rails in Africa, Asia-Pacific, Europe and the Americas. Its coverage table shows, for each country, whether onramps and offramps are supported and the expected settlement time, and notes that “real-time” usually means within one business hour rather than instant (Fern docs). Coverage changes often, so check the table for the corridors you need.
Pricing and Revenue for Developers
Fern’s API was in private beta according to its docs, with developers creating an account on the dashboard and choosing a billing plan (Fern docs). Fern does not publish a full fee schedule, so pricing needs to be confirmed with the team.
Fern also lets partners earn revenue: developers can add a fee on conversions that Fern settles monthly in USD or USDC, charge users for accounts and wallets, share yield on funds at rest in some products, and share card interchange (Fern docs).
Who Is Fern For?
- Fintechs and neobanks that want stablecoin onramps and offramps without building bank and exchange integrations themselves
- Payment and payroll apps that need to move money across borders between local currencies and stablecoins
- Wallets and crypto apps that want fiat connectivity with KYC and KYB handled by a compliance team
- Businesses and remote teams looking for an onchain spending and savings account
Pros and Cons
Pros
- One API for fiat, stablecoin and crypto conversion across several chains
- Built-in compliance program with white-labelled onboarding
- Revenue sharing options for developer partners
- Backing of a larger stablecoin payments company after the Rain deal
Cons
- Integration into Rain means product names, pricing and onboarding may change
- No public fee schedule
- Fiat corridor coverage varies, and some currencies support offramps only
- Centralized, custodial infrastructure: users rely on Fern, Rain and their partners
Fern vs. Alternatives
Fern competes with other stablecoin infrastructure APIs such as Bridge, which Stripe owns, and with Rain itself, whose platform covers accounts, cards and money movement through a single API (Rain). After the acquisition, the practical question for new customers is whether to integrate Fern directly or go through Rain’s combined offering. For a wider comparison, see our guide to the best stablecoin payment APIs.
Conclusion
Fern is a useful piece of stablecoin plumbing: a compliance-led API for moving money between local currencies, stablecoins and crypto. It is not a decentralized stablecoin and has no token. Since the Rain acquisition, Fern’s Multiplex is becoming part of Rain’s platform, and existing customers are being supported through the transition. Developers evaluating Fern in 2026 should speak to both teams about how new integrations will be handled.
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FAQs:
1. What is Fern?
A stablecoin payments API for onramps, offramps, FX and crypto-to-crypto transfers, now owned by Rain.
2. Does Fern have its own stablecoin or token?
No. Fern moves existing stablecoins such as USDC, USDT, PYUSD and EURC and does not issue its own coin or governance token.
3. Who acquired Fern?
Rain, a stablecoin payments and card infrastructure company, announced the deal on December 2, 2025.
4. Which chains does Fern support?
Ethereum, Arbitrum, Base, OP Mainnet, Polygon and Solana.
5. Can existing Fern customers keep using it?
Yes. Fern and Rain say existing integrations and API keys stay active while products are merged.
