Most YAML errors are whitespace, and most YAML tools report them as something else. YamlHippo's parser is written by hand, character by character, and keeps the stack of indentation levels that are open — so when a line does not fit, it says so in those words: Line 7, col 1: indented 3 spaces but siblings use 2 (in $.spec.ports), with a link to the siblings it disagrees with. It fixes what a clipboard does to YAML on paste, shows anchors and aliases as what they are, gives every custom tag — !Ref, !Person — its own colour and a reference built from all its uses, and flags the values a YAML 1.1 parser would read differently: no as false, 3.10 as 3.1, 0755 as octal. JsonHippo's sibling, with the same tree, schema and order-blind diff.
macOS · Windows · Linux · Web · Vanilla JS · jQuery · GPL-3.0
What it does
YAML viewer with pinpoint errors
Pinpoint errors for YAML that will not parse — down to the indentation: “indented 3 spaces but siblings use 2”. Plus smart paste that fixes tabs and curly quotes, a tree you can filter by key, path or tag, and warnings for the values other parsers read differently. In your browser or on your desktop; nothing is uploaded.
Says where it broke
A hand-written parser with an indentation stack gives the line, column and path of every error — and for indentation, how deep the line is and how deep its siblings are. It passes the official YAML test suite.
Smart paste
Tabs in the indentation, siblings at 3 spaces and 2, curly quotes from a word processor and no-break spaces from a web page are fixed on paste, with an Undo. Block scalars are left exactly as written.
The values parsers disagree on
country: NO is false to a YAML 1.1 parser, python: 3.10 is 3.1, 0755 is 493 and 1:30 is 90. YamlHippo reads YAML 1.2 and flags each one rather than silently picking a side.
A tree you can filter
By key or value, regex, a path like $..image, or a tag like !Ref. Aliases point at their anchors instead of copying them, and a stream of --- documents gets a document switcher.
Custom tags, followed
Every custom tag gets its own colour, a chip, a tinted subtree and a legend. The Types tab unions every use of each tag into a reference: which fields always appear, which are optional, and where their types disagree.
Format, diff, schema
Format keeps the comments; Copy as JSON says what did not survive the trip; Diff ignores key and list order; Schema infers a JSON Schema from a sample, as JSON or YAML.
Nothing leaves your machine
No server, no account, no tracking. Files are read locally and never uploaded.
Downloads
YamlHippo on your desktop
On the desktop, YamlHippo comes inside ViewHippo, the herd's desktop app: one download that opens JSON, YAML and Markdown files, each in the viewer made for it. ViewHippo — · free to download and use. No account required.
Every ViewHippo build is published on
GitHub Releases,
where you will also find the release notes and every previous version. Prefer to
build it yourself? The source
is right there.
Where to go next
YamlHippo, everywhere else
The herd page is the introduction. These are the places the project actually lives.
