If you're reading this, you probably don't need an explanation of what an onramp is. You need to know what separates onramp APIs that scale from ones that will bottleneck your product—and how to integrate without burning engineering quarters on payments plumbing.
This guide covers the evaluation criteria that actually matter, the architecture patterns that work, and how Lightspark Grid handles fiat-to-crypto conversion through a single API. Fiat currency—government-issued money like USD, EUR, or BRL that isn't backed by physical commodities—remains the primary medium of exchange for most users. As Web3 applications continue to gain adoption, seamless fiat-to-crypto conversion has become critical for onboarding users who don't yet hold cryptocurrency.
What Separates Onramp APIs: An Evaluation Framework
Not all fiat onramp infrastructure is built the same. Here's what to look for when you're comparing options.
Payment Rails and Geographic Coverage
The number of supported countries matters less than which rails are supported in each country. Bank transfers are table stakes. What you want is access to local instant payment systems: SEPA Instant in Europe, PIX in Brazil, SPEI in Mexico, UPI in India, Faster Payments in the UK, FedNow and RTP in the US.
These rails settle in seconds, not days. If your onramp provider only offers standard bank transfers in a given corridor, your users wait longer and you lose conversions to competitors with faster options.
Questions to ask:
- Which instant payment rails are supported by country?
- Is crypto settlement available globally, or restricted by geography?
- Can users fund with cards, bank transfers, and mobile wallets—or just one?
Quote and Rate-Locking Mechanics
This is underrated. When a user initiates a purchase, what exchange rate do they get? How long is it valid? What happens if they don't complete funding in time?
Onramp providers handle this differently. Some give indicative rates that shift by the time the transaction settles. Others lock rates for a window—typically 1 to 15 minutes—so users know exactly what they'll receive before committing.
Locked quotes reduce support tickets, improve UX, and let you display precise amounts at checkout. If your provider doesn't offer rate locking, you're passing FX risk to your users (or absorbing it yourself).
Questions to ask:
- Does the provider offer locked quotes with guaranteed rates?
- How long do quotes remain valid?
- Can you lock either the sending amount or the receiving amount (useful for invoice payments)?
Funding Models: Pre-Funded vs. Just-in-Time
There are two patterns for how funds flow into an onramp:
Pre-funded accounts: Your platform or your users maintain a balance. When they want to buy crypto, funds are debited instantly from that balance. This works well for platforms with existing wallet infrastructure or frequent traders.
Just-in-time (JIT) funding: The user requests a quote, receives payment instructions (bank details, reference code), and sends funds. Once the provider receives the payment, the conversion executes automatically. This works well for one-time purchases or users who don't want to pre-load accounts.
The best infrastructure supports both. JIT is typically better for on-ramps (users funding cryptocurrency purchases). Pre-funded is typically better for off-ramps (users cashing out).
Compliance Infrastructure
Every onramp needs to handle KYC and AML. The question is whether you handle it or your provider does.
Some providers require you to pass through user data and manage verification yourself. Others offer hosted KYC/KYB flows—users complete identity verification through the provider's interface, and you inherit their compliance stack.
For regulated entities (banks, licensed money transmitters), you likely want to use your own compliance infrastructure. For startups and non-regulated platforms, hosted compliance dramatically reduces time-to-launch and ongoing overhead.
Questions to ask:
- Does the provider offer hosted KYC/KYB, or do you need to bring your own?
- What jurisdictions are covered?
- For crypto rewards or crypto payment use cases, is recipient KYC required—or just sender KYB?
Fee Transparency
Onramp pricing can be opaque. Some providers, like some crypto exchanges, quote a spread on the exchange rate. Others charge a percentage. Some do both, plus fixed fees, plus hidden markups in the rate.
What you want: a fee breakdown in the quote response that shows exactly what the user pays, what the recipient receives, and what's taken in fees. This lets you model unit economics accurately and display honest pricing to users.
Questions to ask:
- Are fees shown transparently in the quote, or embedded in the rate?
- Is it a spread, percentage, fixed fee, or combination?
- Are there different fee tiers based on volume or payment method?
Developer Experience
You'll live with this integration for years. The quality of the API, documentation, and tooling matters.
Look for:
- Clean REST APIs with predictable patterns
- Comprehensive docs with real request/response examples
- A sandbox environment that mirrors production behavior
- Webhooks for real-time status updates
- SDKs in your language (or at minimum, a Postman collection to get started)
Poorly documented APIs cost engineering weeks. A sandbox that doesn't match production costs, debugging cycles. Check the GitHub repo if it's public—activity and issue responsiveness tell you a lot.
Architecture Patterns for Onramp Integration
Once you've selected a provider, here's how the onboarding integration typically works.
The Quote → Fund → Execute Flow
Most onramp APIs follow this pattern:
- Create a quote. Specify the source (user's payment method or account), destination (crypto wallet), and amount. The API returns a locked exchange rate, fees, and expiration time.
- Fund the quote. For JIT funding, the user sends funds to the payment instructions provided. For pre-funded accounts, this step is skipped—funds are already available.
- Execute the quote. Once funded (or immediately, for pre-funded sources), you call the execute endpoint. The provider converts the funds and delivers crypto to the destination wallet.
- Receive confirmation. Webhooks notify you when the transaction completes, fails, or requires attention.
Handling Rate Expiration
Quotes expire. Users get distracted, payment rails have delays, things happen. Your integration needs to handle this gracefully.
Best practice: store the quote parameters (source, destination, amount, locked side) so you can recreate an expired quote with a fresh rate. Don't force users to re-enter information—just fetch a new quote and show them the updated rate.
When to Use Immediate Execution
Some APIs offer an "immediate execute" flag that creates and executes a quote in a single call, without waiting for user confirmation.
This is useful for:
- Rewards payouts (user isn't choosing an amount)
- Micro-transactions (rate differences are negligible)
- Programmatic conversions (treasury operations, automated rebalancing)
Don't use it for user-initiated purchases where they expect to see the rate before committing.
How Grid Handles Onramps
Lightspark Grid provides API-first infrastructure for fiat-to-crypto and crypto-to-fiat conversion. Here's how it maps to the evaluation criteria above.
Single API for Fiat, Stablecoins, and Bitcoin
Grid doesn't require you to integrate separate vendors for bank rails, card processing, and crypto conversion. One API handles:
- Fiat-to-fiat transfers (USD → EUR, BRL → MXN)
- Fiat-to-crypto conversion (USD → BTC, EUR → USDC)
- Crypto-to-fiat conversion (BTC → USD, USDC → EUR)
- Crypto-to-crypto transfers
You specify source and destination; Grid routes across the optimal rails automatically.
The Quote System
Grid's quote system locks exchange rates for 1–15 minutes depending on payment type. Each quote includes:
- Exact sending and receiving amounts
- Exchange rate
- Itemized fees (fixed, variable, counterparty)
- Expiration time
- Payment instructions (for JIT funding)
You can lock either the sending amount ("user wants to spend $100") or the receiving amount ("recipient must receive exactly 0.001 BTC"). Fees are deducted from the sending side and displayed transparently—no hidden markups.
Example quote response:
Coverage: 65 Countries, Local Rails
Grid supports local instant payment rails across 65 countries:
- US: ACH, Wire, RTP, FedNow
- Europe (32 countries): SEPA, SEPA Instant
- UK: Faster Payments
- Brazil: PIX
- Mexico: SPEI
- India: UPI, IMPS
- Singapore: PayNow, FAST
Bitcoin and stablecoin transactions are supported globally with no geographic restrictions.
Funding Options
Grid supports both funding models:
Pre-funded: Maintain balances in internal accounts. When you create and execute a quote, funds are debited instantly. Best for off-ramps and platforms with existing balance infrastructure.
Just-in-time: Create a quote and receive payment instructions—bank details, reference codes, or wallet addresses. Once Grid receives the funds, the quote executes automatically. Best for on-ramps and one-time purchases.
You can fund via ACH, SEPA Instant, wire transfers, PIX, Lightning, and more.
Compliance: Two Paths
Grid offers flexibility depending on your regulatory status:
Hosted KYC/KYB: For non-regulated platforms, Grid handles identity verification. Users complete the flow through Grid's hosted interface, and you inherit the compliance stack. Faster time-to-launch, less overhead.
Bring your own: For regulated entities (banks, licensed fintechs), you handle KYC/KYB through your existing processes. Grid accepts your verified customers.
For rewards and payouts, only the paying entity needs KYB verification. You can send Bitcoin to any wallet address without requiring recipient KYC—useful for cashback programs, creator payouts, and promotions.
Delivery
Crypto settles to the user's wallet via the Lightning Network (for Bitcoin) or supported blockchain rails (for stablecoins). Grid handles all on-chain logic, wallet operations, and conversion—you interact with a clean API.
For Bitcoin rewards, Grid supports delivery to Spark wallets or other Lightning-compatible destinations.
Off-Ramps: The Other Direction
The same infrastructure works in reverse. Users sell crypto and receive fiat to their bank accounts.
The flow:
- User holds crypto in a pre-funded account (or sends crypto to a Grid-provided address)
- You create a quote specifying crypto source and fiat destination (user's external bank account)
- Execute the quote
- Fiat settles via local rails—SEPA Instant, Faster Payments, PIX, ACH, etc.
Supporting both on-ramp and off-ramp creates a closed loop. Users move freely between fiat and crypto without leaving your platform. You capture fees in both directions and reduce churn to competitors.
Build vs. Buy
Some teams consider building onramp infrastructure in-house. Here's what that requires:
- Money transmission licenses in each jurisdiction you operate
- Banking partnerships for fiat rails (ACH, SEPA, local schemes)
- Liquidity relationships with exchanges or OTC desks
- Card processor integrations (if supporting card funding)
- KYC/AML vendor contracts and ongoing compliance maintenance
- Fraud detection and chargeback management
- On-chain infrastructure for crypto settlement
While centralized onramp APIs offer speed and compliance infrastructure, decentralized finance (DeFi) protocols provide an alternative approach that lets users swap crypto assets directly through automated market makers without intermediaries—though this typically requires users to already hold crypto to pay transaction fees.
For most companies, this represents 12–18 months of work and significant ongoing overhead. The math rarely justifies it unless onramp infrastructure is your core product.
The alternative: integrate with purpose-built infrastructure. Modern onramp APIs let you go live in days. You inherit the provider's compliance stack, liquidity network, and rail coverage. Your engineering team focuses on product differentiation rather than payments plumbing.
Getting Started
Grid offers a sandbox environment that mirrors production—test the full flow from quote creation to settlement without moving real funds.
To start integrating:
- Review the Ramps documentation
- Explore the API with the Postman collection
- Check out the GitHub repo
- Contact sales to discuss your use case and get API credentials
