About EDN ↔ JSON

Convert between Clojure EDN and JSON formats. Part of the DevTools Surf developer suite. Browse more tools in the Converters collection.

Use Cases

• Clojure developers sharing data with JavaScript/Python services
• Data engineers converting Datomic query results to JSON
• Teams migrating from Clojure backends to polyglot architectures
• API developers bridging EDN-based services with JSON consumers

Tips

• Map EDN keywords to JSON string keys automatically
• Handle EDN sets by converting them to JSON arrays
• Preserve EDN tagged literals as annotated JSON objects

Fun Facts

• EDN (Extensible Data Notation) was created by Rich Hickey as part of the Clojure ecosystem — it's essentially 'Clojure data literals as a format' and was formalized around 2012.
• Unlike JSON, EDN natively supports sets, keywords, symbols, and tagged elements — making it more expressive but also harder to map losslessly to JSON.
• Datomic, the immutable database created by Rich Hickey, uses EDN as its native query and transaction format, making EDN-to-JSON conversion essential for integrating with non-Clojure systems.

FAQ

What is EDN?

Extensible Data Notation — Clojure's data serialization format. JSON-like but with additional types: keywords (:foo), symbols, sets (#{...}), and tagged literals (#inst "2020-01-01").

How are EDN keywords converted to JSON?

Keywords become strings with a leading colon by default: `:foo` → `":foo"`. Toggle 'strip colon' for cleaner JSON (`"foo"`) at the cost of round-trip accuracy.

What about EDN sets?

JSON has no set type. Sets become arrays with deduplicated values. Round-tripping back to EDN loses the set identity — a known limitation.

Does it support tagged literals?

Common ones yes — `#inst` becomes ISO 8601 strings, `#uuid` becomes UUID strings. Custom tags pass through as `{tag: "#name", value: ...}` objects.