YAML formatter that points at the tab

Because the specification forbids tab characters in indentation outright, and no parser will accept them. The reason is that indentation in YAML is counted in columns and a tab has no fixed width — one file would nest differently depending on whether it was read with a tab of two, four or eight, so the format simply outlaws the character rather than picking a number. Tabs are legal inside a scalar value, which is why the error you get points at a line that looks fine. This page names every offending line, and the “Convert tabs” switch expands the leading tabs to your chosen indent so the file can be read at all; with it off, the document is handed back untouched rather than half-fixed.

Because YAML 1.1 resolves 16 different words to booleans — y, n, yes, no, on and off in several capitalisations — and most of the world is still running 1.1 parsers. PyYAML, Ruby's psych and Go's gopkg.in/yaml.v2 all read `country: no` as `country: False`, which is the reason the Norway problem has its own name. YAML 1.2 narrowed the core schema to true and false only, so newer readers such as yaml.v3 and the JavaScript yaml package leave `no` alone — and that split is worse than either rule, because the same file now means two things. The fix is to quote it: "no" is a string in every version. This page flags each of the 16 rather than changing your value for you.

No. Every scalar is copied across as the characters you wrote, so a version pinned as 1.10 does not become 1.1, a leading zero survives, and key order is exactly the order in the file. What moves is the indentation, the spacing after a colon and, if you ask for it, the quote style — and even then quotes are only ever converted or removed, never added, because wrapping a bare 8080 in quotes would turn an integer into a string. A formatter for a format where indentation is meaning has to be more conservative than one for JSON, not less.

Both are valid, and the file parses identically either way. Putting the dash flush with its key is what the YAML specification's own examples do and what Kubernetes manifests usually look like; indenting it one level is what Prettier, docker-compose documentation and most editors produce, and it makes the nesting easier to follow when a sequence holds mappings that hold more sequences. Pick one and apply it to the whole repository — the switch here exists so you can normalise a file that has been edited by people who chose differently.

The body is preserved down to the last space, and only the block as a whole is shifted. Everything under a `|` or `>` header is data — a shell script, a certificate, an embedded config — so relative indentation inside it is kept exactly and the whole block moves together to sit under its key. The one case that is not touched at all is a header carrying an explicit indentation indicator such as `|2`, because the number in the header counts columns from the parent: move the block and the number becomes a lie. Those blocks are copied out verbatim and noted in the panel.

It reports the failures it can see from the structure — tabs in indentation, duplicate keys in one mapping, values a YAML 1.1 parser will re-type — but it is not a full validator and does not pretend to be. It reads the block structure line by line rather than building a document model, which is exactly what lets it re-indent a file a strict parser would reject outright, and which is also why it cannot tell you that an anchor points at nothing. For a yes-or-no verdict with the line the parser stopped on, the YAML validator on this site does that job.

Because a flow collection spread over several lines has its own continuation rules, and re-indenting it means re-deciding where each item sits. A `[1, 2, 3]` written on one line is a scalar-shaped value and is copied through as it stands; the same list broken across four lines is taken as a region and reproduced exactly, with a note saying so. The same applies to explicit key syntax (`? key`) and to a plain scalar that continues onto a following line — three constructs where guessing would be worse than leaving them be.