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diff --git a/crates/typst-library/src/loading/json.rs b/crates/typst-library/src/loading/json.rs
new file mode 100644
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+++ b/crates/typst-library/src/loading/json.rs
@@ -0,0 +1,101 @@
+use ecow::{eco_format, EcoString};
+use typst_syntax::Spanned;
+
+use crate::diag::{At, SourceResult};
+use crate::engine::Engine;
+use crate::foundations::{func, scope, Str, Value};
+use crate::loading::Readable;
+use crate::World;
+
+/// Reads structured data from a JSON file.
+///
+/// The file must contain a valid JSON value, such as object or array. JSON
+/// objects will be converted into Typst dictionaries, and JSON arrays will be
+/// converted into Typst arrays. Strings and booleans will be converted into the
+/// Typst equivalents, `null` will be converted into `{none}`, and numbers will
+/// be converted to floats or integers depending on whether they are whole
+/// numbers.
+///
+/// Be aware that integers larger than 2<sup>63</sup>-1 will be converted to
+/// floating point numbers, which may result in an approximative value.
+///
+/// The function returns a dictionary, an array or, depending on the JSON file,
+/// another JSON data type.
+///
+/// The JSON files in the example contain objects with the keys `temperature`,
+/// `unit`, and `weather`.
+///
+/// # Example
+/// ```example
+/// #let forecast(day) = block[
+///   #box(square(
+///     width: 2cm,
+///     inset: 8pt,
+///     fill: if day.weather == "sunny" {
+///       yellow
+///     } else {
+///       aqua
+///     },
+///     align(
+///       bottom + right,
+///       strong(day.weather),
+///     ),
+///   ))
+///   #h(6pt)
+///   #set text(22pt, baseline: -8pt)
+///   #day.temperature °#day.unit
+/// ]
+///
+/// #forecast(json("monday.json"))
+/// #forecast(json("tuesday.json"))
+/// ```
+#[func(scope, title = "JSON")]
+pub fn json(
+    /// The engine.
+    engine: &mut Engine,
+    /// Path to a JSON file.
+    ///
+    /// For more details, see the [Paths section]($syntax/#paths).
+    path: Spanned<EcoString>,
+) -> SourceResult<Value> {
+    let Spanned { v: path, span } = path;
+    let id = span.resolve_path(&path).at(span)?;
+    let data = engine.world.file(id).at(span)?;
+    json::decode(Spanned::new(Readable::Bytes(data), span))
+}
+
+#[scope]
+impl json {
+    /// Reads structured data from a JSON string/bytes.
+    #[func(title = "Decode JSON")]
+    pub fn decode(
+        /// JSON data.
+        data: Spanned<Readable>,
+    ) -> SourceResult<Value> {
+        let Spanned { v: data, span } = data;
+        serde_json::from_slice(data.as_slice())
+            .map_err(|err| eco_format!("failed to parse JSON ({err})"))
+            .at(span)
+    }
+
+    /// Encodes structured data into a JSON string.
+    #[func(title = "Encode JSON")]
+    pub fn encode(
+        /// Value to be encoded.
+        value: Spanned<Value>,
+        /// Whether to pretty print the JSON with newlines and indentation.
+        #[named]
+        #[default(true)]
+        pretty: bool,
+    ) -> SourceResult<Str> {
+        let Spanned { v: value, span } = value;
+        if pretty {
+            serde_json::to_string_pretty(&value)
+        } else {
+            serde_json::to_string(&value)
+        }
+        .map(|v| v.into())
+        .map_err(|err| eco_format!("failed to encode value as JSON ({err})"))
+        .at(span)
+    }
+}