YAML to JSON Gotchas: When Types and Indentation Break

YAML is stricter than it looks

Converting YAML to JSON seems trivial — both are nested key/value structures. The traps appear because YAML infers types and JSON does not.

Gotcha 1: boolean coercion

active: yes
enabled: no
debug: on

Becomes:

{ "active": true, "enabled": false, "debug": true }

If you wanted the strings "yes"/"no", quote them. This is the single most common surprise.

Gotcha 2: numbers

YAML guesses numeric types, and JSON has no integer/float distinction — but the value can still shift:

zip: 01234      # becomes 1234 (leading zero dropped)
ratio: 1e3      # becomes 1000
hex: 0xFF       # becomes 255

Quote anything that must stay exactly as written.

Gotcha 3: null vs empty

note:          # empty value
other: ~       # ~ is null

Both become null in JSON, losing the distinction between “empty string” and “absent”.

Gotcha 4: indentation

YAML is whitespace-sensitive. One wrong space changes the tree:

a:
  b: 1
   c: 2     # misindented -> error or wrong nesting

JSON’s explicit braces avoid this, but you lose the readability that made you use YAML.

Gotcha 5: multiline strings

YAML | (literal) and > (folded) blocks expand into strings with specific newline handling. JSON stores them as one escaped string, so line breaks and trailing newlines can differ from what you expect.

Gotcha 6: anchors and aliases

defaults: &d { retries: 3 }
job:
  <<: *d

Anchors (&d) and merges (<<: *d) have no JSON equivalent and are flattened during conversion — usually what you want, but worth knowing it is not reversible.

Convert safely

Paste YAML and get JSON (and back) with the YAML to JSON tool on Toolbox.

Related tools

• YAML to JSON on Toolbox
• JSON ↔ YAML on Toolhub
• JSON to YAML on DevTools

Next steps

• When the JSON itself will not parse, start with Unexpected token in JSON.
• Text bound for a URL is UTF-8 first — see UTF-8 vs GBK.