Know whether a message will be accepted
This is the question behind almost every other one. A message can be perfectly valid ISO 20022 and still be refused by a clearing system, because the scheme rules sit above the standard itself.
AskISO checks all three layers: the schema, the lint rules, and whichever scheme profile applies to you. Each finding names the rule that produced it and the exact path in the document, so it can be handed to whoever owns that field rather than interpreted first.
Start here: check a message. It runs in your browser and nothing is uploaded.
Meet the structured address mandate
A cross-border payment carrying an unstructured postal address is rejected. Not flagged, not downgraded — rejected. Swift deferred the November 2026 cutover on 27 August and will confirm replacement timing by December.
The gap is rarely located in the payment engine. It sits in the customer data feeding that engine, which is precisely why remediation takes considerably longer than institutions anticipate. AskISO reports which addresses are unstructured, where they are, and what each one needs.
Start here: what the deferred structured-address requirement changes.
Migrate from SWIFT MT
MT101, MT103, MT104, MT107, MT202, MT204 and MT940 convert to their ISO 20022 equivalents, and each converts back. Every conversion carries a fidelity report naming what was mapped, derived, shortened or lost.
That report matters more than the conversion itself. Translation between MT and MX loses detail inherently, and a tool returning only the output is asking you to assume nothing disappeared.
Start here: paste an MT message into the workspace.
Catch it in the pipeline, not at the counterparty
A malformed message caught during a build costs you a build. The same message caught by a correspondent costs an investigation, a repair, and a customer asking where their money went.
AskISO runs as a command line tool, as a GitHub Action, and as a language server that marks problems in your editor while you type. Findings come out as SARIF, so they appear in code scanning beside everything else your pipeline reports.
Start here: the developer documentation.
Give an AI assistant something it can cite
An assistant questioned about ISO 20022 answers from memory, confidently, and occasionally incorrectly. AskISO ships a Model Context Protocol server exposing the same engine as ten tools, so the assistant looks the answer up and cites the rule identifier it used.
Beyond looking things up, thirteen further MCP servers let an assistant do the work: compose a payment, read the statement that returns, reconcile it, remediate an address, and seal the outcome into an evidence pack. Each validates its own output before returning it, and none of them moves money.
Start here: the MCP servers, or the integration guide.
What it costs
Nothing. It is open source under Apache-2.0 or MIT, with no account, no API key and no licence server. The only thing you supply is the schemas, downloaded free from the Registration Authority, and only when you want full schema validation.
Where to start reading
The knowledge centre arranges everything published here by the question you arrived with, rather than by what each page is called.