Spell-out vs Say-as-word

JSON is said as a word: “JAY-son” /ˈdʒeɪsən/, like the name Jason.

A minority say “JAY-sawn” with a fuller second vowel; both are fine.

• It stands for JavaScript Object Notation.
• Collocations: parse the JSON, a JSON payload, return JSON, JSON schema.
• Almost nobody spells out “J-S-O-N” — it is always a word.

If in doubt, “Jason” the name is your safe model.

YAML is said as a word: “YAM-el” /ˈjæməl/, rhyming with “camel”.

The first syllable is “yam” (the vegetable), not “yay”.

• It stands for YAML Ain’t Markup Language (a recursive acronym).
• Collocations: a YAML file, YAML config, valid YAML, YAML indentation.
• Spelling out “Y-A-M-L” sounds unnatural; use the word.

Pair it mentally with “camel” and you will always get the vowel right.

SOAP is said as a word: “soap” /soʊp/, exactly like the washing kind.

It originally stood for Simple Object Access Protocol.

• Collocations: a SOAP endpoint, a SOAP envelope, call the SOAP service, SOAP vs REST.
• It is an XML-based messaging protocol, contrasted with REST.
• Never spell it out — it is always one syllable.

Like REST, it is one of those acronyms that conveniently spells a real English word.

JWT is normally spelled out: “J-W-T” — though some say “jot” /dʒɒt/.

The other three are all said as words.

• REST = “rest” (Representational State Transfer).
• CRUD = “crud” (Create, Read, Update, Delete).
• AJAX = “AY-jaks” (Asynchronous JavaScript and XML).

JWT (JSON Web Token) resists a clean single-word form, so letters dominate, with “jot” as a playful alternative the spec itself endorses.

URL is normally spelled out: “U-R-L” /juː ɑːr ɛl/.

A small group jokingly says “earl” /ɜːrl/, but that is informal and can confuse listeners.

• It stands for Uniform Resource Locator.
• Collocations: copy the URL, a URL parameter, the base URL, a malformed URL.
• Compare GUI, which goes the other way — said as “gooey”, not “G-U-I”.

So default to the letters for URL; save “earl” for relaxed banter among teammates.