Products FM Marketplace
Multi-dealer marketplace
FM Liquidity Match
Saas for electronic trading
FM White Label
B2B White Label Crypto Trading Platform
FM Pulse
Real-time market data analytics
FM Space
Counterparty selection
Clients Banks & brokers
Neobanks, crypto-native and FX brokers
Payment providers
PSPs, payment gateways, on/off ramp
OTC desks
Crypto trading desks, retail platforms
Buy-side
Passive funds, hedge funds, asset managers
Liquidity providers
Market makers, proprietary shops
Prime brokers
Agency and risk-principle brokers
Stablecoin issuers
Next gen of fintech
Company About Careers Blog Media kit Referral Legal Imprint Operating rules Privacy Policy Risk Disclosure Support Contact us

For Customers Log in

S2S integration Meaning

S2S (Server-to-Server) integration is a method of connecting two different software systems where the communication happens directly between their servers, bypassing the user's web browser. In fintech, S2S is the preferred method for high-security tasks like processing payments, verifying identities (KYC), or executing trades, as it prevents sensitive data from being exposed to potential client-side Man-in-the-Middle attacks.A common S2S workflow involves Webhooks and Postbacks.

For example, when a user makes a crypto payment at a merchant's site, the merchant's server sends an S2S request to a payment gateway (like BitPay) to create an invoice. Once the payment is confirmed on-chain, the gateway's server sends a Postback directly to the merchant's server to confirm the order is paid.

Because this happens behind the scenes, it is much harder for a user to fake a payment confirmation by editing the code in their browser.The primary challenge of S2S integration is State Synchronization. Both servers must stay perfectly in sync despite network latency or temporary outages.

To handle this, developers use Idempotency Keys, which ensure that if a server sends the same request twice (perhaps because the first one timed out), the receiving server will only process it once. This is critical in finance to prevent Double Charging a user or Double Counting a deposit.

← Back to Glossary

Explore our services

Providing liquidity in the cryptocurrency market?
Authorize on our platform and do it smarter with FM Pulse.

FM Marketplace

A reliable and high-performance crypto liquidity marketplace for institutions and businesses.

Learn more

FM White Label

Launch your fully branded B2B crypto trading platform in under one week.

Learn more

FM Liquidity Match

Crypto OTC-as-a-Service infrastructure for enhanced monetization and trade control.

Learn more

Scale your business, leave the hard work of your trading needs to us

Reduce your integration costs and operational risk across multiple access points with our platform

Get started

Important Disclaimer:

Finery Markets BVI Limited (“Finery Markets”) provides software, technology infrastructure, and related Information and Communication Technology (ICT) services on a Software-as-a-Service (“SaaS”) basis. Finery Markets acts solely as a software vendor and does not operate a trading platform, does not intermediate, match, execute, clear, or settle transactions, and does not engage in any activities that would require regulatory authorisation under applicable laws.

Finery Markets’ software is non-custodial and is provided exclusively to licensed institutional entities that act as independent operators of their own environments. All counterparties are solely responsible for establishing and maintaining their own bilateral trading and settlement relationships. Finery Markets is not a party to any such arrangements and assumes no responsibility for the conduct, verification, or compliance obligations of any users of the software.

Nothing on this website shall be construed as a financial promotion, investment advice, or an offer to engage in regulated activities. Access to and use of the software is strictly limited to clients who have entered into a software licensing agreement with Finery Markets. Persons located in jurisdictions where such access is restricted should not rely on this website or any of its contents.

Additional notice to UK visitors: This website and associated communications are not intended to constitute a financial promotion under The Financial Services and Markets Act 2000 (Financial Promotion) Order 2005 (as amended) and related guidance. Access to services provided by Finery Markets is limited to regulated entities, professional clients and eligible counterparties as set out by the Financial Conduct Authority. UK users are not permitted to use this website for the services of Finery Markets if they don't fall within these categories.