Common Data Formats for Web APIs

Back to API Design
Arjit Sharma
01 Min

Before data can travel between systems over a network, it must be serialized*(converted into a format suitable for transmission)*. Choosing the right format impacts speed, readability, and interoperability.

What to Consider When Choosing a Data Format →

  1. Low Latency - Smaller, faster-to-transfer payloads
  2. Fast Processing - Easy for machines to parse
  3. Human Readable - Helpful for debugging and documentation
  4. Flexible - Ease to introduce changes over time
  5. Interoperable - Works well across platforms and systems

Text-Based Formats

Textual formats are human-readable, widely supported, and easy to debug making them ideal for public APIs. JSON, XML, and CSV are data representation formats that use Unicode characters (text) and support encoding in many languages.

JSON (JavaScript Object Notation)

The most common data format for web APIs.

Advantages -

  • Faster than XML
  • Native browser support
  • Human-readable
{
  "name": "Arjit",
  "age": 22,
  "city": "Bengaluru",
  "isStudent": false,
  "hobbies": ["anime", "music", "sports"]
}

XML (eXtensible Markup Language)

More verbose than JSON and suitable for complex structures. Used in wireless communication industry like Personal digital assistants.

Advantages -

  • Strong tooling (XPath, XQuery)
  • Still used in SOAP and enterprise integrations
<message>
  <status>success</status>
  <code>200</code>
  <text>Hello World</text>
</message>

Binary Data Formats

This format is Machine friendly, is schema dependent and is standardized unlike text data formats. It is best where performance matters (and human readability doesnt).

Advantages -

  • Small size hence lower bandwidth usage
  • Faster to parse by machines

Common Binary Formats -

FormatUse Case
ProtoBufGoogle’s gRPC, microservices
AvroBig Data, Apache Kafka
ThriftFacebook’s RPC framework
BSONBinary JSON used in MongoDB

Example: ProtoBuf

message Node {
  required int64 node_id = 1;
  optional string node_content = 2;
  repeated string node_links = 3;
}
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