Contents
"Instant swap" describes dozens of sites that look the same: two dropdowns, an amount, a button. Underneath, they differ in ways that decide whether your money arrives, how much of it, and what happens when something goes wrong. The reviews that rank them tend to rank marketing: bonuses, "trusted by" counters, star ratings that no one can check.
This post does something narrower. It lists criteria that can be verified by looking at a service, says why each one matters to a person about to send money, and then scores Sablebolt against them — honestly, including the ones where the answer is "not yet". It does not score other services, because we have not verified them and would be guessing. The value is the method; the last section shows how to apply it to any site in about ten minutes.
The criteria
| # | Criterion | What to look for | Why it matters |
|---|---|---|---|
| 1 | Account required? | Can you reach the deposit address without an e-mail, a password or a wallet connection? | Every account is a record that can be leaked, locked or asked for later |
| 2 | Custody after the swap | Does the payout go to the address you gave, or into a balance the service holds for you? | A balance is money you have to ask for; an address is money you have |
| 3 | USDT networks offered | Which networks appear for USDT, named explicitly | The network decides fees, confirmations and whether the receiver can accept it at all |
| 4 | Network fee shown before sending | Is the payout network fee a visible figure, subtracted before "You get", before you send anything? | A fee that appears after the deposit cannot be refused |
| 5 | Status page with both hashes | After the deposit, can you see the deposit transaction hash and the payout transaction hash, linked to explorers? | The payout hash is the only proof the money left; without it you cannot check an exchange's claim that nothing arrived |
| 6 | Fixed or floating rate | Does the service say which, and when the rate is set? | "Instant" services usually settle at the rate when the deposit confirms; a service that hides this will surprise you on a moving market |
| 7 | Contact and policy pages | A support address, a security contact, terms and a privacy notice that say what the service keeps | When a swap stalls you need a place to write and a statement of what they hold about it |
| 8 | Machine-readable truth | Does the service publish its routes, limits and quotes in a form a program can read (an API description, text versions of pages)? | A published API is a claim that can be checked by anyone; a form alone cannot |
Two criteria often found in reviews are left out on purpose. Volume and user counts cannot be verified from outside and are not repeated here. Ratings on review sites measure who paid attention to the review site, not who paid out correctly.
Criterion by criterion
1. Account required?
Open the service, pick a pair and an amount, and press the button. Count what is asked before a deposit address appears. The honest answer is one of: nothing beyond an address; an e-mail; an account with a password; a wallet connection and a signature. The last one is sometimes dressed as "no account", but a connected wallet is an identity, and a signature can authorise more than the swap.
A service that needs no account cannot lose your account. It also cannot hold your money for you, which is criterion 2.
2. Custody after the swap
Follow the money through the description on the site. In an instant swap the deposit goes to a one-time address, the swap is executed, and the payout is sent on the other network. The question is where it ends: at the address you typed, or in a balance inside the service that you withdraw later. The second kind is an exchange with a simpler front; it has withdrawal limits, withdrawal fees and the ability to pause withdrawals.
During the minutes of the swap, any instant service controls the deposit; that is how the swap happens. What you can check is whether it holds anything for you after the payout, and whether the site says so plainly.
3. USDT networks offered
USDT is one name on several networks, and a service may list "USDT" and mean only one of them. Open the asset list and read the network labels. Then check the address format the form accepts for each: a T… address for TRON, 0x… for Ethereum and BNB Smart Chain, UQ… or EQ… for TON. A service that lists two networks under one 0x… label without a way to tell them apart will, sooner or later, pay out on the wrong one. The USDT page shows how the four networks differ.
4. Network fee shown before sending
Enter a small amount — the minimum, or a little above — and look at the figures. There should be an estimate, a line for the network fee, and a "You get" that is the estimate minus the fee. The small amount matters because the network fee is flat and shows up clearly in percent: on a 20 USDT swap it may be a visible slice, on 2,000 it rounds away. A service that shows only "You get" has not necessarily hidden anything, but you cannot tell what part is rate and what part is fee, and you cannot compare networks. USDT network fees compared explains why the payout fee differs from a wallet fee and why that difference is not a trick.
5. Status page with both hashes
The status page is where a swap is judged. After the deposit it should show the deposit transaction hash as soon as the network sees it, the payout hash as soon as it is sent, and each as a link to the network's explorer. With both hashes you can prove to anyone — a receiver, an exchange's support, yourself — that the money left and where it went. Without the payout hash you are trusting a progress bar.
If you have not swapped with a service, read its how-it-works page for a statement about the status page and the hashes; if it says nothing, assume nothing.
6. Fixed or floating rate
Floating means the swap settles at the market rate when the deposit confirms; the estimate you saw is indicative. Fixed means the rate is locked when the swap is created, usually for a limited time and at a wider spread. Neither is wrong, but a service must say which it offers and when the rate is set. Look on the fees page, in the terms, and next to the estimate itself.
7. Contact and policy pages
Find the support address and try to find a second channel. Find the security contact (many sites publish it at /.well-known/security.txt). Read the terms for the sections on failed swaps and on what the service keeps about a swap. Read the privacy notice for what is and is not collected. Note what is marked as a draft or missing; a service that labels its gaps is telling you more than one that fills them with boilerplate.
8. Machine-readable truth
This is the newest criterion and the easiest to check. Look for an API description (commonly /openapi.json), a text index for assistants (/llms.txt), and text versions of pages. A service that publishes its routes and quote arithmetic in a file has committed to them in public; anyone can call the endpoint and compare it with the form. It also means an AI assistant you ask about the service is reading the service's own statements rather than a reviewer's.
Sablebolt against the criteria
Scored on 11 October 2026 from what the site does, not what it plans. Where the honest answer is partial, it says so.
| # | Criterion | Sablebolt | Verified how |
|---|---|---|---|
| 1 | Account required? | No. The form asks for the amount, the address you send from, the receiving address and, where the receiver needs one, a memo. It never asks for an e-mail, a password, a wallet connection or a signature. | /how-it-works, "What we ask for" and "What we never ask for" |
| 2 | Custody after the swap | No balances held. The deposit goes to a one-time address and the payout to the address you named. During the swap the deposit is handled by the side executing it, as in any instant swap. | /about; /how-it-works |
| 3 | USDT networks | Four: TRON (TRC-20), Ethereum (ERC-20), BNB Smart Chain (BEP-20), TON. Not Solana, not Polygon. The form checks the address format per network and has a memo field for TON. | /coin/tether; /v1/assets |
| 4 | Network fee shown before sending | Yes. The form shows the estimate, the network fee and "You get" (estimate minus fee); the estimate refreshes every 60 seconds; the minimum appears under the amount field. In the API: amountTo, networkFee, receiveAmount. | the form; /fees; /openapi.json |
| 5 | Status page with both hashes | Yes. /status/{id} shows the stage, the deposit address and both transaction hashes linked to the explorers of each network. The same fields (txIn, txOut) are in the API. | /how-it-works; /openapi.json |
| 6 | Fixed or floating | Floating only, set when the deposit confirms. Fixed-rate swaps are not offered; the site says so rather than hiding it. | /how-it-works, "The rate"; /openapi.json |
| 7 | Contact and policy pages | Partly. Support and security addresses are published, with /.well-known/security.txt. Terms and privacy pages exist and are marked "draft for review" while their text is being finalised; the Telegram channel is not yet listed. | /support; /about; /terms; /privacy |
| 8 | Machine-readable truth | Yes. /llms.txt, a markdown twin of every page, /openapi.json, an agent-skills index and an RSS feed. | How Sablebolt talks to machines |
Three further facts a careful reader will want, with the same honesty:
- The rate includes the margin. The fees page says the estimate already includes the service's margin and the cost of liquidity, with no separate service fee on top. There is no published percentage, because a floating rate does not have one; the way to see the real cost is to compare "You get" with the market price of the amount you send.
- The swap is executed through a liquidity partner. The site does not name it. The partner sees the same swap details the site does: the two addresses, the amounts, the hashes. This is stated on the privacy notice.
- No third-party scripts. The site's security headers allow scripts from its own origin only and connections only to its own API, and the privacy notice says there are no advertising or analytics trackers. You can read the headers in your browser's developer tools.
How to run this check on any service in ten minutes
You need a browser, a small amount in mind, and no money sent. Two minutes per group.
Minutes 1–2: the form. Pick USDT on the network you hold and any destination. Enter the minimum amount. Write down: the estimate, whether a network fee is a separate line, the "You get" figure, and whether a minimum is shown. Press the button and stop at the first thing the service asks for. Address only, or e-mail, or password, or wallet connection? That is criteria 1 and 4.
Minutes 3–4: the networks. Open the asset list and list every USDT entry with its network label. Paste a TRON address (T…) into a form set to Ethereum and see whether it is refused. Look for a memo field when TON or XRP is the destination. That is criterion 3.
Minutes 5–6: the money's path. Read the how-it-works page. Find the sentence that says where the payout goes and whether anything is held for you afterwards. Find the sentence about the rate: fixed, floating, and when it is set. Find the sentence about the status page and the hashes. If any of the three sentences is missing, write "not stated". That is criteria 2, 5 and 6.
Minutes 7–8: the pages behind the form. Open /support (or the contact page), the terms, the privacy notice and /.well-known/security.txt. Note which exist, which are drafts, and which contain a real address. That is criterion 7.
Minutes 9–10: the machine files. Open /llms.txt, /openapi.json and /robots.txt. If the first two exist, open one API endpoint from the description — a quote for the same amount you typed — and compare the figures with the form. If they match, the form is telling the truth in public. That is criterion 8.
Write the eight answers down with the date. A service that scores well today may change; a dated note is worth more than a memory.
Checklist: what a good answer looks like
FAQ
Why not just rank the services?
Because a ranking needs the same verified data for every row, and we have it only for ourselves. Scoring others from their marketing would repeat exactly what this post argues against. The criteria are published so that you, or anyone, can produce the rows.
Does "no account" mean the swap leaves no record?
No. Both transactions are public on their networks, and the service and its liquidity partner keep the swap's addresses, amounts, hashes and time. "No account" means nothing is created that identifies you to the service beyond the swap itself.
Is a floating rate worse than a fixed one?
It is different. A fixed rate protects you from a moving market during the deposit and costs a wider spread; a floating rate settles at the market when the deposit confirms. For USDT to USDT between networks the rate stays close to one to one either way. What matters is that the service says which it uses.
What is the single most important criterion?
The payout hash on the status page. It is the one piece of evidence that settles every dispute: the money left, on this network, to this address, at this time.
Sablebolt's terms are marked as drafts. Should that worry me?
It should be counted, which is why it is in the table. The pages exist and carry the support address; the text is being finalised and is labelled as such rather than presented as final.
Can an AI assistant run this check for me?
Most of it. It can read the pages and the machine files and call a quote endpoint; the post on how Sablebolt talks to machines shows what that looks like here. What it cannot do is press the button and see what the form asks for — that two-minute step is yours.