FAQ

Glossary terms questions

Frequently asked questions drawn from the halfin glossary terms pages. Each one links to a standalone answer.

Glossary terms questions

Every question below was authored on a glossary terms page and now has its own answer page. Pick the one that matches what you are working on.

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Every question, one page each.

Are stablecoins exactly equal to one dollar?The peg is a design target, not an identity: a dollar-pegged stablecoin trades very close to one dollar but moves in small amounts around it. On halfin…
Can a customer charge back a crypto payment they made through halfin?No. A confirmed on-chain payment is final and cannot be reversed by the customer or their bank — there is no issuer or card network to claw the funds…
Can a customer dispute a crypto payment the way they dispute a card charge?Not in the same way. A confirmed on-chain payment is final, so there is no bank or card network that can force the funds back. A customer can still…
Can a customer pay a halfin invoice in a native coin?Yes. halfin supports native coins as payable assets directly — BTC, ETH, SOL, XRP, TRX, and the BNB Smart Chain's base coin — alongside stablecoins. The…
Can a customer pay an Ethereum invoice from a layer-2 like Base or Arbitrum?No — each network is distinct, even for the same asset. USDC on Ethereum, Base, and Arbitrum share a token standard but are separate deposits on separate…
Can a gas fee make a payment arrive short?It can, if the payer's wallet takes the fee out of the amount being sent rather than adding it on top — common when someone asks a wallet to send its…
Can a payment platform keep all its keys in cold storage?No. Detecting deposits, sweeping them, and sending payouts automatically require signing transactions without a human in the loop, which means some keys…
Can a payout be reversed once it is sent?No. Once halfin has signed, broadcast, and confirmed a payout, it is an on-chain transfer that is final — no third party can pull it back. That is why…
Can a refund be partial?Yes. A refund is reasoned about relative to the amount paid on the original invoice, so it can return the full paid amount or part of it — for example a…
Can I pay a halfin invoice with a wrapped token?No — halfin detects and credits the native assets and first-class tokens of the chains it supports, and there is no wrapped-token gate. A wrapped form has…
Can I settle in fiat with halfin?No. halfin is a digital-asset payment platform, so settlement currencies are crypto assets — typically a dollar-pegged stablecoin that tracks the currency…
Can one API key do everything on my account?Not by default — keys are scoped to specific operations, so a key only does what it was granted permission to do. This lets you issue a read-only key for…
Can someone double-spend a payment they already sent me?Only within the settlement window, before the transaction is confirmed. A transaction seen in the mempool or in a single recent block can still be…
Do I need a block explorer to use halfin?No. halfin monitors the supported chains itself and reports invoice state in the dashboard and over webhooks, so detection and confirmation happen…
Do I need the native coin to send a stablecoin?Yes. Sending a token such as USDT or USDC is still a transaction on the underlying chain, and the gas fee for that transaction is charged in the chain's…
Do I need to bridge anything to accept payments with halfin?No. halfin accepts each asset on the networks it runs gates for, and credits a payment on the chain it arrives on. There is no cross-chain bridging step…
Do I pay gas to receive an ERC-20 token?No. The gas fee for an ERC-20 transfer — paid in ETH — is borne by the sender who initiates it; as the recipient you do not pay it. How busy Ethereum is…
Do sandbox payments move real funds or settle on-chain?No. The sandbox operates on test data, authenticated with test API keys, and never moves real funds or settles a transaction on a blockchain. Its job is…
Does a crypto wallet actually store my coins?No. The balances live on the blockchain, recorded against addresses; the network keeps that record. What the wallet stores is the private keys that…
Does a payment in the mempool count as paid?No. A transaction in the mempool has been broadcast but not yet included in a block, so it has zero confirmations and can still be delayed, dropped, or…
Does a payment platform have to use a hot wallet?In practice, yes. Sending payouts and sweeping deposits automatically means signing transactions without a human in the loop, which requires keys that are…
Does a transaction hash mean the payment is final?No. The hash exists as soon as the transaction is broadcast, but a payment is only treated as settled after it reaches the per-chain confirmation…
Does an HMAC signature encrypt the message?No. HMAC authenticates a message — it proves the message came from a holder of the shared secret and that it was not altered — but it does not hide the…
Does completing KYB mean a business is licensed or regulated?No. KYB is a verification process that a provider runs at onboarding; it is not a status. Passing KYB confirms that a provider has checked who you are —…
Does halfin charge the gas fee?No. A gas fee is a network cost paid by the sender's wallet to the blockchain that processes the transfer. halfin does not set it and does not receive it…
Does multisig protect against both theft and loss?Yes, when the keys are kept apart. Because M signatures are required, compromising a single key is not enough to move funds, and because there are spare…
Does the gas limit apply to every chain halfin supports?No. Gas limit is an EVM concept, so it applies to Ethereum, the L2s Base, Arbitrum, and Polygon, and BNB Smart Chain. Bitcoin, Tron, XRP, and Solana meter…
Does the price swing of a cryptocurrency land on the merchant?Not on halfin. Invoices are fiat-anchored: you bill a fiat amount, halfin maps it to the payable cryptocurrency amount at the live rate and locks it when…
Does the quote change while the customer is paying?No. The quote is the amount computed at activation and it holds for the life of the invoice, so market movement during the payment window does not change…
Does the token standard change depending on the chain?Yes. The same token can follow different standards on different chains: USDC on Ethereum is an ERC-20 token, USDC on Solana is an SPL token. The standard…
Does the travel rule apply to every crypto transfer?No. It applies to transfers above a defined threshold that move between regulated providers, and the specifics — what counts as a regulated provider, the…
Does using crypto avoid AML obligations?No. Anti-money-laundering obligations follow the movement of value, not the payment rail. A business accepting crypto is subject to the same kind of…
How deep can a reorg go?It depends on the chain. The vast majority of reorgs are one or two blocks deep and happen routinely at the tip; deeper reorgs are rare and, on chains…
How do I move from the sandbox to live?Switch from your test API key to a live one. Because the sandbox mirrors the production API's endpoints, fields, and lifecycle states, the integration you…
How do I protect my business from double-spends?Act on settlement, not on first sight. Don't fulfil an order or release goods the moment a payment appears in a wallet or explorer — wait until it is…
How does a merchant resolve a dispute on halfin?By deciding the claim is valid and issuing a refund. halfin refunds are outbound payments the merchant initiates and approves, so returning money to a…
How is a crypto payment gateway different from a card payment gateway?Both stand between the buyer paying and the merchant's systems, accept a payment, verify it, and report the result. The difference is the rails. A card…
How is a payout different from a refund?A refund is the reason — returning money to a customer for an order that already paid — and a payout is the mechanism that delivers it: a fresh outbound…
How is a webhook different from an API call?An API call is one your application makes to halfin and waits on. A webhook is the reverse: halfin makes the HTTP call to an endpoint you registered…
How is an underpayment different from an unpaid or expired invoice?An unpaid invoice has received no deposit at all, and an expired invoice reached its deadline without being settled. An underpayment is the opposite of…
How is machine-to-machine settlement different from a normal payment?It is about who drives it. A normal payment usually has a person in the loop — an operator who reads a dashboard, checks an amount, and approves the…
How is sanctions screening different in crypto?The obligation is the same — you cannot transact with a sanctioned party — but the mechanics adapt to how blockchains work. Because a transfer is tied to…
How long does finality take?It depends entirely on the chain. A fast-finality network can settle a payment after a few blocks, while a chain with more reorg risk needs more. halfin…
How many confirmations does a payment need?It depends on the chain. There is no universal number — a fast-finality network can be safe after a few blocks, while a chain with more reorg risk needs…
If a mass payout fails partway, is it safe to resubmit the whole list?Yes, provided each line keeps its original idempotency_key. The platform recognises the lines that already succeeded and skips them, creating only the…
Is a block explorer the same as a wallet?No. A wallet holds keys and lets you send and receive funds; a block explorer holds nothing and can only read the public ledger. An explorer can show any…
Is a bridge the same as a wrapped token?They are related but not the same. A bridge is the mechanism that moves an asset between chains; a wrapped token is the representation a bridge typically…
Is a chargeback the same as a refund?No. A refund is a payment the merchant chooses to send back to the customer. A chargeback is a forced reversal imposed through the card networks after the…
Is a cryptocurrency the same as a token?Loosely, yes — both are digital assets on a blockchain. The useful distinction is that some cryptocurrencies are native to their chain (Bitcoin on the…
Is a deposit address the same as a wallet?No. A wallet manages the private keys that control funds; a deposit address is one receiving destination derived from those keys. A single wallet can hold…
Is a destination tag the same as a memo?They serve the same purpose — routing a payment to the right account behind a shared address — but the name differs by network. The XRP Ledger calls it a…
Is a layer-2 less secure than its base chain?A layer-2 inherits its security from the layer-1 it settles to, rather than running fully independent consensus like a sidechain. Its transactions are…
Is a mass payout a separate batch endpoint on halfin?No. A mass payout is a fan-out over the same single-payout API — the request carries multiple lines and each line is processed as its own payout. There is…
Is a payment final as soon as it is on the blockchain?Not immediately. Being included in a block starts the process, but the recent tip of a chain can reorganize and undo a transaction that was only in the…
Is a payment settled as soon as it appears on-chain?Not quite. Inclusion in a block starts settlement, but the most recent history of many chains can still be reorganized, which would undo the transaction…
Is a refund the same as reversing the original crypto payment?No. A confirmed on-chain payment is final and cannot be reversed at the protocol level. A refund is a separate outbound transfer the merchant sends back…
Is a stablecoin a token?Usually, yes. The dollar-pegged stablecoins halfin accepts — USDT and USDC — are tokens issued on host chains: USDT exists as an ERC-20 token on Ethereum…
Is a transaction in a block already final?Not necessarily. On chains with probabilistic finality the most recent blocks can still be reorganized, which would undo a transaction that was only in…
Is a wrapped token the same as the asset it represents?Not on-chain. A wrapped token is a separate token on a different network that stands in for the underlying asset; it is redeemable one-to-one for it, but…
Is AML the same as KYC or KYB?No, but they are related. KYC (know your customer) and KYB (know your business) are the identity-verification steps that establish who a counterparty is —…
Is an overpaid invoice still considered paid?Yes. An overpayment covers the amount owed in full, so the invoice is settled and the sale can proceed. The difference is that the customer sent more than…
Is an SPL token a coin?No. "SPL token" describes a token managed by Solana's Token Program — the format, not a specific coin. Solana's native currency is SOL, which pays…
Is ERC-20 a cryptocurrency?No. ERC-20 is a standard — a set of rules — for how a token behaves on Ethereum, not a coin itself. Many tokens follow it, including the Ethereum versions…
Is halfin a payment gateway?Yes. halfin is a crypto payment gateway: a merchant integrates once and uses it to accept digital-asset payments through invoices and hosted or…
Is it safe to share a public key or a receiving address?Yes. The public key is derived from the private key one way only, and the receiving address is derived from the public key — neither lets anyone recover…
Is receiving dust a security risk?Receiving it does nothing on its own. The concern is a dusting attack, where someone sends tiny amounts to many addresses and then watches the blockchain…
Is sanctions screening something halfin is certified for?No. Sanctions screening is a control a business runs continuously to avoid dealing with prohibited parties — it is not a certification or licence a…
Is the EVM a blockchain?No. The EVM is the runtime — the virtual machine that executes smart contracts — not a chain itself. Ethereum is a blockchain that uses the EVM, and other…
Is the settlement currency the same as the currency the customer pays in?Not necessarily. The payment currency is what a customer chooses at checkout; the settlement currency is the asset the merchant decides to hold the…
Is the travel rule something halfin is certified for?No. The travel rule is an obligation that may apply to certain regulated providers when they transmit value — it is not a certification or license a…
Is this glossary specific to halfin or is it general crypto vocabulary?Both. Each definition is a general, technically correct explanation of the term as it is used across crypto and payments, followed by a short note on what…
Is TRC-20 a coin?No. TRC-20 is a token standard on the Tron blockchain — a shared set of rules that fungible tokens follow. The network's native coin is TRX, which pays…
Is TRC-20 USDT the same as ERC-20 USDT?They represent the same dollar of value but are different on-chain objects. TRC-20 USDT lives on Tron; ERC-20 USDT lives on Ethereum. They use comparable…
Is USDC the same as USDT?No. Both are stablecoins that target one US dollar, but they are issued by different companies and are distinct tokens. A wallet holds USDC and USDT as…
Is USDT on Ethereum the same as USDT on Tron?It is the same dollar of value but a different on-chain token. USDT on Ethereum follows the ERC-20 standard; USDT on Tron follows Tron's TRC-20 standard…
Is USDT the same as USDC?No. Both are stablecoins that target one US dollar, but they are issued by different companies and are distinct tokens. A wallet holds USDT and USDC as…
Is wrapping the same as balance conversion on halfin?No. Wrapping moves an asset's value onto a foreign chain through a bridge and a reserve. halfin's balance conversion swaps one supported asset for another…
Should I generate a new idempotency key when a request times out?No — that is exactly the case where you should keep the same key. A timeout means you do not know whether the server processed the request. Retrying with…
What does custody mean in crypto?Custody is the question of who holds the private keys to a set of funds. Because the only way to move crypto is to sign a transaction with the matching…
What does M-of-N mean in a multisig wallet?N is the total number of keys that govern the wallet, and M is how many of them must sign for a transaction to be valid. A 2-of-3 wallet has three keys…
What happens if a customer pays on the wrong network?A deposit address is tied to one chain, so it must be paid on the network it was issued for — a USDT address on Tron is not the same as a USDT address on…
What happens if a deposit is smaller or larger than the invoice amount?The amount a deposit carries is set by the payer, so it can land short of or above what an invoice requested. halfin reconciles the confirmed amount…
What happens if a private key is lost or stolen?Both outcomes are permanent. A stolen key lets whoever holds it sign and drain the address; a lost key means no one can produce the signature the network…
What happens if I forget the destination tag?The payment still reaches the address, because the tag is a separate field and not part of the address. The problem is attribution: the receiving service…
What happens if I reuse an idempotency key for a different request?The server treats it as a retry of the original request and replays the original result, ignoring the new request body. That is correct for an actual…
What happens if the crypto price moves after the invoice is created?Nothing changes for the customer or the merchant. The payable crypto amount is computed from the live rate when the invoice activates and then frozen, so…
What happens if the crypto price moves after the rate is locked?Nothing changes for the customer. The locked amount is the conversion computed at activation, so market movement during the payment window does not alter…
What happens if the gas limit is too low?The transaction runs until it exhausts the limit, then the network reverts it — the transfer does not complete. The gas already burned is still charged…
What happens to my invoice if the deposit's block is reorged away?Nothing is left stranded. halfin credits reorg-aware, so a deposit only marks an invoice paid once the chain has reached that network's confirmation…
What happens to the extra amount in an overpayment?halfin credits the full value received, including the part above the amount owed, and exposes the difference through the invoice.overpaid event. What…
What happens to the funds from an underpayment?They are real, confirmed funds and stay accounted for against the invoice — they are not lost or rejected. Because an on-chain deposit is irreversible…
What happens when the rate lock expires?The quote is no longer valid. On halfin the lock is tied to the invoice expiry, so once the window passes the invoice expires and the locked amount no…
What if a customer pays after the invoice has expired?A deposit that arrives after expiry is not settled against the stale quote. halfin surfaces it as a late-deposit event rather than silently applying the…
What is the difference between a cold wallet and a hot wallet?A cold wallet keeps its private keys offline and signs only through a deliberate manual step, so a remote attacker has nothing to reach. A hot wallet…
What is the difference between a custodial and a non-custodial wallet?In a non-custodial wallet, the user holds the private keys and signs their own transactions, with full control and full responsibility for protecting the…
What is the difference between a fiat-anchored invoice and a crypto-denominated one?A crypto-denominated invoice is priced directly in an asset — bill 0.0021 BTC — and its fiat value floats with the market until it clears. A fiat-anchored…
What is the difference between a hot wallet and a cold wallet?A hot wallet keeps its private keys on an internet-connected system so it can sign transactions automatically; a cold wallet keeps the keys offline and…
What is the difference between a native coin and a token?A native coin is the base asset issued by a blockchain's own protocol — BTC on Bitcoin, ETH on Ethereum, SOL on Solana — and it is what every transaction…
What is the difference between a private key and a public key?The private key is the secret you keep; the public key is derived from it, and the receiving address from the public key. You can share the public key and…
What is the difference between a public key and an address?They sit on the same chain of derivation. The public key is computed from the private key; the address is a shorter, encoded form computed from the public…
What is the difference between a quote and a rate lock?They are two sides of the same event. The rate lock is the mechanism that fixes the fiat-to-crypto conversion rate at a single instant; the quote is the…
What is the difference between a seed phrase and a private key?A private key authorizes spending from one address. A seed phrase regenerates the entire set of private keys a wallet holds, so it controls every address…
What is the difference between a stablecoin and a coin like Bitcoin?Bitcoin and Ether have freely floating prices that move with the market. A stablecoin is designed to hold a steady value by tracking a reference such as…
What is the difference between a token and a coin?A coin is a blockchain's own native asset — BTC on Bitcoin, ETH on Ethereum, SOL on Solana — and it pays that chain's transaction fees. A token is an…
What is the difference between a webhook secret and an HMAC signature?The webhook secret is the shared key; the HMAC signature is the value computed from that key and the event body. The sender uses the secret to produce a…
What is the difference between gas limit and gas price?The gas limit is the maximum number of gas units a transaction may consume; the gas price is what the sender pays per unit. Multiply them and you get the…
What is the difference between KYB and KYC?KYC (Know Your Customer) verifies an individual person; KYB (Know Your Business) verifies a legal entity and the people who control it. KYB is broader…
What is the difference between self-custody and third-party custody?With self-custody the owner holds their own keys and no one else can sign for them — full control and full responsibility, including no recourse if a key…
What should I do if my webhook secret is exposed?Rotate it. Once a secret is exposed — committed to a repository, printed in a log, leaked from a third party — anyone holding it can forge events your…
What stops an automated retry from settling twice?An idempotency key. The caller attaches a stable value that names the logical action; the server does the work once and replays the original result on any…
When is a deposit considered settled?Not the moment it appears on-chain. Recent blocks can be reorganized, which would undo a deposit that was only in the discarded branch. halfin waits for…
Where do I find the transaction hash for a payment?It is recorded against the invoice or deposit in the dashboard and returned in the API representation of that record. Payment-related webhook events also…
Where do I put the API key in a request to halfin?In the X-API-Key HTTP request header, sent over HTTPS from your backend. halfin reads that header to identify your merchant account and to check that the…
Where should I go after reading a definition?Term pages link to each other and to the relevant product, asset, and FAQ pages, so you can follow a concept from its definition into how halfin actually…
Which EVM chains does halfin accept?halfin runs EVM gates for Ethereum, Base, Arbitrum, Polygon, and BNB Smart Chain (BSC), covering both the native coins and the ERC-20 stablecoins it…
Which stablecoins can I accept with halfin?Two: USDT (Tether) on Tron (TRC-20), Ethereum (ERC-20) and Solana, and USDC on Ethereum (ERC-20), Solana and Base. A customer pays whichever they hold on…
Why can't I just spend dust like any other balance?You can, technically — dust is real value and it is yours. The problem is economic: the network fee to send it is larger than the balance itself, so…
Why do Ethereum, Base, and Polygon addresses look the same?Because they all use the EVM, which defines the address format the same way for each. An address is a 42-character `0x…` hex string on every…
Why do I have to verify the webhook signature?Your webhook URL is a public HTTP endpoint, so anything could send a forged payload to it — including a fake "payment received" message. halfin signs…
Why do on-chain payments have no chargebacks?Once a transaction is confirmed and final on the blockchain, no bank or third party can reverse it — there is no issuer to claw the funds back and no…
Why does halfin support several blockchains instead of one?Each blockchain is a separate network with its own assets, fees, and speed, and a payment on one chain is invisible to the others. Supporting several lets…
Why does one invoice sometimes have more than one transaction hash?Each on-chain transaction has its own hash. If a customer underpays and then sends a second transaction to make up the difference, that top-up is a…
Why does the comparison need to be constant-time?A comparison that returns as soon as it finds a differing byte takes slightly longer the more leading bytes match. An attacker who can send many requests…
Why does USDT exist on several networks?Tether issues USDT natively on multiple blockchains, so the same dollar of value can live on Tron (TRC-20), Ethereum (ERC-20), Solana and others. The…
Why is the gas fee different on different networks?Each blockchain prices block space on its own, and the fee rises and falls with how busy the chain is. The same stablecoin transfer can cost very little…
Why isn't my payment marked paid the moment it appears?Appearing in a block is not the same as being final. Recent blocks can be reorganized, which would undo a transaction that was only in the discarded…
Why might a transaction sit in the mempool for a long time?Block producers generally pick transactions by fee, so a transaction offering a low fee can wait while higher-fee ones are mined first, especially when…
Will halfin ever ask for my seed phrase?No. halfin signs on a merchant's behalf, so blockchain keys and any seed material stay inside the platform — a merchant never handles a halfin seed…