JSON

What it means

JSON, JavaScript Object Notation, is a simple text format for writing structured data. Data is written as name-value pairs inside curly braces and lists inside square brackets, so a file can be read both by people and by programs without complicated processing.

The format knows only a few value types: string, number, boolean, null, object and array. That simplicity has made it the standard for exchanging data between applications, especially through an API or REST API, where it has largely replaced the older XML.

Although the name refers to JavaScript, JSON is language-independent and almost every programming language and database works with it. It is used in configuration files, for storing settings, in application exports and in webhooks that send notifications about events.

How it works in practice

For websites, JSON-LD matters: a way of writing structured data using the Schema.org vocabulary. A block inserted in the page tells search engines that it describes a company, an article, questions and answers or a term definition, which can improve how it appears in search results.

In accounting you meet JSON when systems are connected. Banks offering open banking, payment gateways, online shops and iPaaS tools send transactions and orders in this format, and the accounting software loads them as documents according to an agreed structure.

When editing by hand, validators help by spotting a missing comma or quotation mark. For regular data exchange it is worth defining a schema, a description of required fields and types, so that both sides can check that a received file matches what was agreed.

What to watch out for

JSON does not prescribe a format for dates or numbers. One system sends a date as year-month-day text, another as a count of seconds, and amounts may arrive as decimals with rounding errors. For financial data it is safer to send amounts in cents or as text with a fixed number of decimal places.

JSON files often contain personal data or credentials, such as API keys in configuration. They must not be stored in public repositories or emailed unprotected, and logs containing full request bodies need the same protection as the database itself.