diff --git a/Cargo.lock b/Cargo.lock
index 4c08108..9480ede 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -55,6 +55,7 @@ version = "1.0.83"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f1174fb0b6ec23863f8b971027804a42614e347eafb0a95bf0b12cdae21fc4d0"
 dependencies = [
+ "jobserver",
  "libc",
 ]
 
@@ -158,6 +159,15 @@ version = "1.0.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "af150ab688ff2122fcef229be89cb50dd66af9e01a4ff320cc137eecc9bacc38"
 
+[[package]]
+name = "jobserver"
+version = "0.1.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "48d1dbcbbeb6a7fec7e059840aa538bd62aaccf972c7346c4d9d2059312853d0"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "libc"
 version = "0.2.147"
@@ -239,6 +249,12 @@ version = "0.2.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3b3cff922bd51709b605d9ead9aa71031d81447142d828eb4a6eba76fe619f9b"
 
+[[package]]
+name = "pkg-config"
+version = "0.3.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7edddbd0b52d732b21ad9a5fab5c704c14cd949e5e9a1ec5929a24fded1b904c"
+
 [[package]]
 name = "powersync_core"
 version = "0.4.0"
@@ -254,6 +270,7 @@ dependencies = [
  "sqlite_nostd",
  "streaming-iterator",
  "uuid",
+ "zstd-safe",
 ]
 
 [[package]]
@@ -494,3 +511,22 @@ name = "winapi-x86_64-pc-windows-gnu"
 version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
+
+[[package]]
+name = "zstd-safe"
+version = "7.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f49c4d5f0abb602a93fb8736af2a4f4dd9512e36f7f570d66e65ff867ed3b9d"
+dependencies = [
+ "zstd-sys",
+]
+
+[[package]]
+name = "zstd-sys"
+version = "2.0.15+zstd.1.5.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eb81183ddd97d0c74cedf1d50d85c8d08c1b8b68ee863bdee9e706eedba1a237"
+dependencies = [
+ "cc",
+ "pkg-config",
+]
diff --git a/crates/core/Cargo.toml b/crates/core/Cargo.toml
index 3839d97..a6f9512 100644
--- a/crates/core/Cargo.toml
+++ b/crates/core/Cargo.toml
@@ -23,6 +23,7 @@ const_format = "0.2.34"
 futures-lite = { version = "2.6.0", default-features = false, features = ["alloc"] }
 rustc-hash = { version = "2.1", default-features = false }
 streaming-iterator = { version = "0.1.9", default-features = false, features = ["alloc"] }
+zstd-safe = { version = "7.2.4", default-features = false }
 
 [dependencies.uuid]
 version = "1.4.1"
diff --git a/crates/core/src/lib.rs b/crates/core/src/lib.rs
index 76edd45..7530d7c 100644
--- a/crates/core/src/lib.rs
+++ b/crates/core/src/lib.rs
@@ -34,6 +34,7 @@ mod version;
 mod view_admin;
 mod views;
 mod vtab_util;
+mod zstd;
 
 #[no_mangle]
 pub extern "C" fn sqlite3_powersync_init(
@@ -62,6 +63,7 @@ fn init_extension(db: *mut sqlite::sqlite3) -> Result<(), ResultCode> {
     crate::view_admin::register(db)?;
     crate::checkpoint::register(db)?;
     crate::kv::register(db)?;
+    crate::zstd::register(db)?;
     sync::register(db)?;
 
     crate::schema::register(db)?;
diff --git a/crates/core/src/zstd.rs b/crates/core/src/zstd.rs
new file mode 100644
index 0000000..22ec9ad
--- /dev/null
+++ b/crates/core/src/zstd.rs
@@ -0,0 +1,46 @@
+extern crate alloc;
+
+use alloc::string::String;
+use core::ffi::c_int;
+
+use sqlite::ResultCode;
+use sqlite_nostd::{self as sqlite, Value};
+use sqlite_nostd::{Connection, Context};
+
+use crate::create_sqlite_text_fn;
+use crate::error::SQLiteError;
+use zstd_safe::DCtx;
+
+fn powersync_zstd_impl(
+    _ctx: *mut sqlite::context,
+    args: &[*mut sqlite::value],
+) -> Result<String, ResultCode> {
+    let arg = args.get(0).ok_or(ResultCode::MISMATCH)?.blob();
+    let dict = args.get(1).ok_or(ResultCode::MISMATCH)?.blob();
+    // TODO: Use a form of streaming decompression to avoid pre-allocating a large buffer.
+    let mut dest = alloc::vec![0u8; 1024 * 20];
+    let mut ctx = DCtx::create();
+    let size = ctx
+        .decompress_using_dict(&mut dest[..], arg, dict)
+        .map_err(|_| ResultCode::CORRUPT)?;
+    dest.truncate(size);
+    let text = String::from_utf8(dest).map_err(|_| ResultCode::MISUSE)?;
+    Ok(text)
+}
+
+create_sqlite_text_fn!(powersync_zstd, powersync_zstd_impl, "zstd_decompress_text");
+
+pub fn register(db: *mut sqlite::sqlite3) -> Result<(), ResultCode> {
+    db.create_function_v2(
+        "zstd_decompress_text",
+        2,
+        sqlite::UTF8,
+        None,
+        Some(powersync_zstd),
+        None,
+        None,
+        None,
+    )?;
+
+    Ok(())
+}