diff --git a/Cargo.toml b/Cargo.toml
index 2f8442c..0a440ba 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -36,7 +36,7 @@ rayon = "1.5.3"
 dashmap = "5.3.4"
 #crossbeam = "0.8.1"
 psutil = "3.2.2"
-bitflags = "2.2.1"
+bitflags = {version ="2.2.1", features = ["serde"] }
 
 #[lib]
 #proc-macro = true
diff --git a/README.md b/README.md
index fa03107..f3a28c5 100644
--- a/README.md
+++ b/README.md
@@ -15,7 +15,7 @@ wget https://github.com/protocolbuffers/protobuf/releases/download/v21.5/protoc-
 ## Run
 Basic run (for example, run on 20 cores):
 ```
-taskset -c 0-19 cargo run --release --  -c "your/command @@" -i input_corpus --core 20
+taskset -c 0-19 cargo run --release --  -c "your/command @@" -i input_corpus -o output --core 20
 ```
 
 Check the usage:
diff --git a/src/datatype.rs b/src/datatype.rs
index d2584d2..7a0156d 100644
--- a/src/datatype.rs
+++ b/src/datatype.rs
@@ -1,9 +1,10 @@
 use crate::mutator::afl_mutator::DeterministicMutationPass;
+use serde::{Deserialize, Serialize};
 use std::sync::atomic::{AtomicU32, Ordering};
 
 pub type TestCaseID = u32;
 
-#[derive(Default, Clone, Debug)]
+#[derive(Default, Clone, Debug, Serialize, Deserialize)]
 pub struct TestCaseMetaInfo {
     #[allow(dead_code)]
     done_pass: DeterministicMutationPass, // All the finished determinsitic passes.
@@ -28,7 +29,7 @@ impl TestCaseMetaInfo {
     }
 }
 
-#[derive(Default, Clone, Debug)]
+#[derive(Default, Clone, Debug, Serialize, Deserialize)]
 pub struct TestCase {
     id: TestCaseID, // The id of the test_case itself or the id of parent. Since we won't use both of them at the same time, we reuse the same slot.
     mutator_id: u32,
diff --git a/src/feedback/bitmap_collector.rs b/src/feedback/bitmap_collector.rs
index 5abe1e2..d12f8c5 100644
--- a/src/feedback/bitmap_collector.rs
+++ b/src/feedback/bitmap_collector.rs
@@ -74,6 +74,7 @@ impl FeedbackCollector for BitmapCollector {
         let mut crash_counter: HashMap<datatype::MutationInfo, u32> = HashMap::new();
         let mut interesting_test_cases = Vec::default();
         let mut crash_test_cases = Vec::default();
+        let mut crashes_vec = Vec::new();
 
         let mut total_timeout: u64 = 0;
         let mut total_crash: u64 = 0;
@@ -100,6 +101,9 @@ impl FeedbackCollector for BitmapCollector {
                 }
                 ExecutionStatus::Crash => {
                     assert!(feedback.contain_test_case());
+                    let test_case_str =
+                        serde_json::to_string(feedback.borrow_test_case().unwrap()).unwrap();
+                    crashes_vec.push(test_case_str);
                     crash_test_cases.push(feedback);
                     *crash_counter.entry(mutation_info).or_insert(1) += 1;
                     total_crash += 1;
@@ -113,7 +117,8 @@ impl FeedbackCollector for BitmapCollector {
 
         // generate monitor data if any
         if total_crash != 0 {
-            self.monitor_data.push(json!({ "crash": total_crash }));
+            self.monitor_data
+                .push(json!({ "crash": total_crash, "testcases": crashes_vec }));
         }
         if total_timeout != 0 {
             self.monitor_data.push(json!({ "timeout": total_timeout }));
diff --git a/src/lib.rs b/src/lib.rs
index 7b82dab..70f84e4 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -965,10 +965,7 @@ pub async fn run_fuzzer_local_async_lock_free_mode(fuzzer: FuzzerConfig) {
 
     let closure = move || {
         // TODO: Fix the testcase minimizer
-        new_queue_frontend::QueueManagerWorker::new_with_seeds(
-            Some(init_seeds.clone()),
-            None,
-        )
+        new_queue_frontend::QueueManagerWorker::new_with_seeds(Some(init_seeds.clone()), None)
     };
     let mut queue_manager_frontend =
         new_queue_frontend::QueueManagerFrontend::new(Box::new(closure));
diff --git a/src/monitor.rs b/src/monitor.rs
index cb1b62f..556a21e 100644
--- a/src/monitor.rs
+++ b/src/monitor.rs
@@ -5,6 +5,11 @@ use std::net::SocketAddr;
 use std::net::{IpAddr, Ipv4Addr};
 use std::sync::{Arc, Mutex, RwLock};
 
+use crate::datatype::TestCase;
+use crate::executor::ExecutionStatus;
+
+use self::output_writer::OutputWriter;
+
 pub mod output_writer;
 pub mod rpc;
 pub mod stats;
@@ -48,6 +53,35 @@ pub fn get_worker_num() -> u32 {
     WORKER_NUM
 }
 
+fn dump_json_testcases(
+    output_writer: &OutputWriter,
+    stats: &serde_json::Value,
+    testcase_type: ExecutionStatus,
+) {
+    let test_case_vec = stats.get("testcases").unwrap().as_array().unwrap();
+    for test_case_val in test_case_vec {
+        let test_case_str = test_case_val.as_str().unwrap();
+        let mut test_case: TestCase = serde_json::from_str(test_case_str).unwrap();
+        match testcase_type {
+            ExecutionStatus::Crash => {
+                test_case.gen_id();
+                match output_writer.save_crash(&test_case) {
+                    Ok(_v) => {}
+                    Err(_e) => println!("Cannot write crash file"),
+                }
+            }
+            ExecutionStatus::Interesting => {
+                output_writer.save_queue(&test_case).unwrap();
+            }
+            ExecutionStatus::Timeout => {
+                test_case.gen_id();
+                output_writer.save_hang(&test_case).unwrap();
+            }
+            _ => {}
+        }
+    }
+}
+
 impl SimpleMonitor {
     fn default() -> Self {
         SimpleMonitor {
@@ -112,10 +146,12 @@ impl Monitor for SimpleMonitor {
 
     // TODO: Receive crash/hang/interesting test cases for saving in disk.
     fn receive_statistics(&self, stats: serde_json::Value) {
+        let mut testcase_type = ExecutionStatus::Ok;
         if let Some(v) = stats.get("exec") {
             self.fuzzer_info.add_exec(v.as_u64().unwrap());
         } else if let Some(v) = stats.get("crash") {
             self.fuzzer_info.add_crash(v.as_u64().unwrap());
+            testcase_type = ExecutionStatus::Crash;
         } else if let Some(v) = stats.get("timeout") {
             self.fuzzer_info.add_timeout_exec(v.as_u64().unwrap());
         } else if let Some(v) = stats.get("interesting_test_case") {
@@ -123,6 +159,13 @@ impl Monitor for SimpleMonitor {
         } else {
             unreachable!();
         }
+        if self.fuzzer_info.get_output_writer().is_some() && stats.get("testcases").is_some() {
+            dump_json_testcases(
+                self.fuzzer_info.get_output_writer().unwrap(),
+                &stats,
+                testcase_type,
+            )
+        }
     }
 
     fn show_statistics(&self) {
diff --git a/src/monitor/stats.rs b/src/monitor/stats.rs
index b567271..fd36a09 100644
--- a/src/monitor/stats.rs
+++ b/src/monitor/stats.rs
@@ -90,6 +90,14 @@ impl FuzzerInfo {
         self.start_time = SystemTime::now();
     }
 
+    pub fn get_output_writer(&self) -> Option<&OutputWriter> {
+        if self.output_writer.is_some() {
+            Some(self.output_writer.as_ref().unwrap())
+        } else {
+            None
+        }
+    }
+
     fn simple_calculate(&self) {
         let elapsed_time = (self.start_time.elapsed().unwrap().as_millis() as u64).max(1);
         let last_print_time = self.last_print_time.swap(elapsed_time, Ordering::Relaxed);
diff --git a/src/mutator/afl_mutator.rs b/src/mutator/afl_mutator.rs
index caa1ec4..36cc603 100644
--- a/src/mutator/afl_mutator.rs
+++ b/src/mutator/afl_mutator.rs
@@ -8,6 +8,7 @@ use rand::seq::SliceRandom;
 use rand::Rng;
 use rand::SeedableRng;
 use rand_distr::WeightedAliasIndex;
+use serde::{Deserialize, Serialize};
 
 //use super::MutatorFunc;
 use core::mem::size_of;
@@ -85,7 +86,7 @@ pub struct BitFlipMutator {
 
 bitflags! {
     //TODO: Each determinitic pass should have a flag.
-    #[derive(Default, Clone, Debug, Copy)]
+    #[derive(Default, Clone, Debug, Copy, Serialize, Deserialize)]
     pub struct DeterministicMutationPass: u32 {
         const BITFLIP1 = 0b1;
         const BITFLIP2 = 0b10;