diff --git a/Cargo.toml b/Cargo.toml
index 5a8e58b..bc2fcbc 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,7 +7,7 @@ edition = "2024"
 axum = "0.8"
 tokio = { version = "1", features = ["full"] }
 rusqlite = { version = "0.35", features = ["bundled"] }
-reqwest = { version = "0.12", features = ["stream"] }
+reqwest = { version = "0.12", features = ["stream", "json"] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 toml = "0.8"
diff --git a/src/lib.rs b/src/lib.rs
index ecdc948..af9f2f2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -4,6 +4,7 @@ pub mod error;
 pub mod hasher;
 pub mod health;
 pub mod server;
+pub mod rebuild;
 pub mod volume;
 
 use std::collections::HashSet;
diff --git a/src/main.rs b/src/main.rs
index 37a045f..2f49fc6 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -45,8 +45,7 @@ async fn main() {
             axum::serve(listener, app).await.unwrap();
         }
         Commands::Rebuild => {
-            eprintln!("rebuild not yet implemented");
-            std::process::exit(1);
+            mkv::rebuild::run(&config).await;
         }
         Commands::Rebalance { dry_run: _ } => {
             eprintln!("rebalance not yet implemented");
diff --git a/src/rebuild.rs b/src/rebuild.rs
new file mode 100644
index 0000000..f7e5aa3
--- /dev/null
+++ b/src/rebuild.rs
@@ -0,0 +1,107 @@
+use std::collections::HashMap;
+
+use crate::config::Config;
+use crate::db;
+
+#[derive(serde::Deserialize)]
+struct NginxEntry {
+    name: String,
+    #[serde(rename = "type")]
+    entry_type: String,
+    #[serde(default)]
+    size: Option<i64>,
+}
+
+/// List all keys on a volume by recursively walking nginx autoindex.
+async fn list_volume_keys(volume_url: &str) -> Result<Vec<(String, i64)>, String> {
+    let http = reqwest::Client::new();
+    let mut keys = Vec::new();
+    let mut dirs = vec![String::new()]; // start at root
+
+    while let Some(prefix) = dirs.pop() {
+        let url = format!("{volume_url}/{prefix}");
+        let resp = http
+            .get(&url)
+            .send()
+            .await
+            .map_err(|e| format!("GET {url}: {e}"))?;
+
+        if !resp.status().is_success() {
+            return Err(format!("GET {url}: status {}", resp.status()));
+        }
+
+        let entries: Vec<NginxEntry> = resp
+            .json()
+            .await
+            .map_err(|e| format!("parse {url}: {e}"))?;
+
+        for entry in entries {
+            let full_path = if prefix.is_empty() {
+                entry.name.clone()
+            } else {
+                format!("{prefix}{}", entry.name)
+            };
+
+            match entry.entry_type.as_str() {
+                "directory" => dirs.push(format!("{full_path}/")),
+                "file" => keys.push((full_path, entry.size.unwrap_or(0))),
+                _ => {}
+            }
+        }
+    }
+
+    Ok(keys)
+}
+
+pub async fn run(config: &Config) {
+    let db_path = &config.database.path;
+
+    // Ensure parent directory exists
+    if let Some(parent) = std::path::Path::new(db_path).parent() {
+        let _ = std::fs::create_dir_all(parent);
+    }
+
+    // Delete old database
+    let _ = std::fs::remove_file(db_path);
+    let _ = std::fs::remove_file(format!("{db_path}-wal"));
+    let _ = std::fs::remove_file(format!("{db_path}-shm"));
+
+    let (writer, ready_rx) = db::spawn_writer(db_path.to_string());
+    ready_rx.await.expect("writer failed to initialize");
+
+    let volume_urls = config.volume_urls();
+
+    // key -> (volumes, size)
+    let mut index: HashMap<String, (Vec<String>, i64)> = HashMap::new();
+
+    for vol_url in &volume_urls {
+        eprintln!("Scanning {vol_url}...");
+        match list_volume_keys(vol_url).await {
+            Ok(keys) => {
+                eprintln!("  Found {} keys", keys.len());
+                for (key, size) in keys {
+                    let entry = index.entry(key).or_insert_with(|| (Vec::new(), size));
+                    entry.0.push(vol_url.clone());
+                    // Use the largest size seen (they should all match)
+                    if size > entry.1 {
+                        entry.1 = size;
+                    }
+                }
+            }
+            Err(e) => {
+                eprintln!("  Error scanning {vol_url}: {e}");
+            }
+        }
+    }
+
+    // Batch insert into SQLite
+    let records: Vec<(String, Vec<String>, Option<i64>)> = index
+        .into_iter()
+        .map(|(key, (volumes, size))| (key, volumes, Some(size)))
+        .collect();
+
+    let count = records.len();
+    writer.bulk_put(records).await.expect("bulk_put failed");
+
+    eprintln!("Rebuilt index with {count} keys");
+}