diff --git a/barretenberg/rust/barretenberg-rs/build.rs b/barretenberg/rust/barretenberg-rs/build.rs
index de21724c68be..fdedb61d7977 100644
--- a/barretenberg/rust/barretenberg-rs/build.rs
+++ b/barretenberg/rust/barretenberg-rs/build.rs
@@ -1,14 +1,10 @@
+use std::path::PathBuf;
+
 fn main() {
-    // Only for ffi feature - link libbb-external from cpp build
+    // Only for ffi feature - link libbb-external
     #[cfg(feature = "ffi")]
     {
-        // Find the cpp build lib directory relative to this crate
-        let manifest_dir = std::env::var("CARGO_MANIFEST_DIR").unwrap();
-        let lib_dir = std::path::Path::new(&manifest_dir)
-            .join("../../cpp/build/lib")
-            .canonicalize()
-            .expect("Failed to find cpp/build/lib - run barretenberg/cpp/bootstrap.sh first");
-
+        let lib_dir = get_lib_dir();
         println!("cargo:rustc-link-search=native={}", lib_dir.display());
 
         // libbb-external.a contains everything needed: barretenberg + env + vm2_stub
@@ -16,3 +12,97 @@ fn main() {
         println!("cargo:rustc-link-lib=dylib=stdc++");
     }
 }
+
+#[cfg(feature = "ffi")]
+fn get_lib_dir() -> PathBuf {
+    // Check if user provided a custom library path
+    if let Ok(lib_dir) = std::env::var("BB_LIB_DIR") {
+        let lib_dir = PathBuf::from(&lib_dir);
+        if lib_dir.join("libbb-external.a").exists() {
+            return lib_dir.canonicalize().unwrap();
+        }
+        panic!(
+            "BB_LIB_DIR is set to {:?} but libbb-external.a not found there. \
+             Build barretenberg locally: cd barretenberg/cpp && ./bootstrap.sh",
+            lib_dir
+        );
+    }
+
+    // Download from GitHub releases
+    let out_dir = PathBuf::from(std::env::var("OUT_DIR").unwrap());
+    let lib_path = out_dir.join("libbb-external.a");
+
+    if !lib_path.exists() {
+        download_lib(&out_dir);
+    }
+
+    out_dir
+}
+
+#[cfg(feature = "ffi")]
+fn download_lib(out_dir: &PathBuf) {
+    let target = std::env::var("TARGET").unwrap();
+    let arch = match target.as_str() {
+        t if t.contains("x86_64") && t.contains("linux") => "amd64-linux",
+        t if t.contains("aarch64") && t.contains("linux") => "arm64-linux",
+        _ => panic!(
+            "Unsupported target for FFI backend: {}. Supported: x86_64-linux, aarch64-linux",
+            target
+        ),
+    };
+
+    // Use BARRETENBERG_VERSION env var, or fall back to crate version
+    let version = std::env::var("BARRETENBERG_VERSION")
+        .unwrap_or_else(|_| env!("CARGO_PKG_VERSION").to_string());
+
+    // Skip download for development versions (0.x.x without BARRETENBERG_VERSION override)
+    // Real releases use the aztec-packages version (e.g., 4.0.0) set via BARRETENBERG_VERSION
+    if version.starts_with("0.") && std::env::var("BARRETENBERG_VERSION").is_err() {
+        panic!(
+            "Cannot download pre-built library for development version {}. \
+             Either set BARRETENBERG_VERSION to a released version, or \
+             set BB_LIB_DIR to point to a local build: cd barretenberg/cpp && ./bootstrap.sh",
+            version
+        );
+    }
+
+    let url = format!(
+        "https://github.com/AztecProtocol/aztec-packages/releases/download/v{}/barretenberg-static-{}.tar.gz",
+        version, arch
+    );
+
+    println!("cargo:warning=Downloading barretenberg static library from {}", url);
+
+    // Download and extract
+    let tar_gz_path = out_dir.join("barretenberg-static.tar.gz");
+
+    let status = std::process::Command::new("curl")
+        .args(["-L", "-f", "-o"])
+        .arg(&tar_gz_path)
+        .arg(&url)
+        .status()
+        .expect("Failed to run curl");
+
+    if !status.success() {
+        panic!(
+            "Failed to download barretenberg static library from {}. \
+             Make sure version v{} exists as a GitHub release.",
+            url, version
+        );
+    }
+
+    let status = std::process::Command::new("tar")
+        .args(["-xzf"])
+        .arg(&tar_gz_path)
+        .arg("-C")
+        .arg(out_dir)
+        .status()
+        .expect("Failed to run tar");
+
+    if !status.success() {
+        panic!("Failed to extract barretenberg static library");
+    }
+
+    // Clean up tar.gz
+    std::fs::remove_file(&tar_gz_path).ok();
+}
diff --git a/barretenberg/rust/bootstrap.sh b/barretenberg/rust/bootstrap.sh
index 4d11c656c172..7b632ad0a8f6 100755
--- a/barretenberg/rust/bootstrap.sh
+++ b/barretenberg/rust/bootstrap.sh
@@ -13,7 +13,9 @@ function build {
     (cd ../ts && yarn generate)
 
     # Build all targets
-    denoise "cargo build --release"
+    # BB_LIB_DIR tells build.rs to use local lib instead of downloading (ffi feature is on by default)
+    # Must use absolute path since build.rs runs from a different directory
+    BB_LIB_DIR="$(cd ../cpp/build/lib && pwd)" denoise "cargo build --release"
 
     # Upload build artifacts and generated source files to cache
     cache_upload barretenberg-rs-$hash.tar.gz target/release barretenberg-rs/src/generated_types.rs barretenberg-rs/src/api.rs
@@ -38,7 +40,63 @@ function test {
   denoise "cargo test --release"
 
   # Run FFI backend tests (requires libbb-external.a from cpp build)
-  RUSTFLAGS="-C link-arg=-Wl,--allow-multiple-definition" denoise "cargo test --release --features ffi"
+  # BB_LIB_DIR tells build.rs to use local lib instead of downloading
+  # Must use absolute path since build.rs runs from a different directory
+  BB_LIB_DIR="$(cd ../cpp/build/lib && pwd)" RUSTFLAGS="-C link-arg=-Wl,--allow-multiple-definition" denoise "cargo test --release --features ffi"
+}
+
+function test_download {
+  echo_header "barretenberg-rs download test"
+
+  # Ensure Cargo is in PATH
+  if [ -f "$HOME/.cargo/env" ]; then
+    source "$HOME/.cargo/env"
+  fi
+
+  # Test that build.rs can download pre-built libraries from GitHub releases
+  # Hide the local library to force download path
+  local lib_path="../cpp/build/lib/libbb-external.a"
+  if [ -f "$lib_path" ]; then
+    mv "$lib_path" "$lib_path.bak"
+    trap "mv '$lib_path.bak' '$lib_path' 2>/dev/null" EXIT
+  fi
+
+  # Clean cargo cache to force rebuild
+  cargo clean -p barretenberg-rs 2>/dev/null || true
+
+  # Build with a known release version
+  local version=${BARRETENBERG_VERSION:-$(gh release list --repo AztecProtocol/aztec-packages --limit 1 --json tagName --jq '.[0].tagName' | sed 's/^v//')}
+  echo "Testing download with version: $version"
+
+  # Retry logic for network flakiness (GitHub releases can be flaky)
+  local max_retries=3
+  local retry=0
+  local success=false
+  while [ $retry -lt $max_retries ]; do
+    if BARRETENBERG_VERSION=$version RUSTFLAGS="-C link-arg=-Wl,--allow-multiple-definition" \
+        cargo test --release --features ffi -p barretenberg-rs 2>&1; then
+      success=true
+      break
+    fi
+    retry=$((retry + 1))
+    if [ $retry -lt $max_retries ]; then
+      echo "Attempt $retry failed, retrying in 5 seconds..."
+      sleep 5
+      # Clean to force re-download
+      cargo clean -p barretenberg-rs 2>/dev/null || true
+    fi
+  done
+
+  if [ "$success" = false ]; then
+    echo "Download test failed after $max_retries attempts"
+    exit 1
+  fi
+
+  # Restore the local library (trap handles this, but be explicit)
+  if [ -f "$lib_path.bak" ]; then
+    mv "$lib_path.bak" "$lib_path"
+    trap - EXIT
+  fi
 }
 
 case "$cmd" in
@@ -58,7 +116,7 @@ case "$cmd" in
   bench|bench_cmds)
     # Empty handling just to make this command valid.
     ;;
-  test|test_cmds)
+  test|test_cmds|test_download)
     $cmd
     ;;
   *)