diff --git a/Cargo.lock b/Cargo.lock
index f30d5ffb4..3c7ce5329 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2192,6 +2192,7 @@ dependencies = [
  "env_logger 0.10.2",
  "garde",
  "hex",
+ "indexmap 2.10.0",
  "itertools 0.14.0",
  "json5",
  "log",
diff --git a/simulator/Cargo.toml b/simulator/Cargo.toml
index b0f372819..89ee9634b 100644
--- a/simulator/Cargo.toml
+++ b/simulator/Cargo.toml
@@ -43,3 +43,4 @@ garde = { workspace = true, features = ["derive", "serde"] }
 json5 = { version = "0.4.1" }
 strum = { workspace = true }
 parking_lot = { workspace = true }
+indexmap = "2.10.0"
diff --git a/simulator/runner/memory/file.rs b/simulator/runner/memory/file.rs
new file mode 100644
index 000000000..158f654b1
--- /dev/null
+++ b/simulator/runner/memory/file.rs
@@ -0,0 +1,163 @@
+use std::{
+    cell::{Cell, RefCell},
+    sync::Arc,
+};
+
+use rand::{Rng as _, SeedableRng};
+use rand_chacha::ChaCha8Rng;
+use tracing::{instrument, Level};
+use turso_core::{Completion, File, Result};
+
+use crate::runner::{
+    clock::SimulatorClock,
+    memory::io::{CallbackQueue, Fd, Operation, OperationType},
+};
+
+pub struct MemorySimFile {
+    pub callbacks: CallbackQueue,
+    pub fd: Arc<Fd>,
+    pub buffer: RefCell<Vec<u8>>,
+    // TODO: add fault map later here
+    pub closed: Cell<bool>,
+
+    /// Number of `pread` function calls (both success and failures).
+    pub nr_pread_calls: Cell<usize>,
+    /// Number of `pwrite` function calls (both success and failures).
+    pub nr_pwrite_calls: Cell<usize>,
+    /// Number of `sync` function calls (both success and failures).
+    pub nr_sync_calls: Cell<usize>,
+
+    pub rng: RefCell<ChaCha8Rng>,
+
+    pub latency_probability: usize,
+    clock: Arc<SimulatorClock>,
+}
+
+type IoOperation = Box<dyn FnOnce(OperationType) -> Result<Arc<turso_core::Completion>>>;
+
+pub struct DelayedIo {
+    pub time: turso_core::Instant,
+    pub op: IoOperation,
+}
+
+unsafe impl Send for MemorySimFile {}
+unsafe impl Sync for MemorySimFile {}
+
+impl MemorySimFile {
+    pub fn new(
+        callbacks: CallbackQueue,
+        fd: Fd,
+        seed: u64,
+        latency_probability: usize,
+        clock: Arc<SimulatorClock>,
+    ) -> Self {
+        Self {
+            callbacks,
+            fd: Arc::new(fd),
+            buffer: RefCell::new(Vec::new()),
+            closed: Cell::new(false),
+            nr_pread_calls: Cell::new(0),
+            nr_pwrite_calls: Cell::new(0),
+            nr_sync_calls: Cell::new(0),
+            rng: RefCell::new(ChaCha8Rng::seed_from_u64(seed)),
+            latency_probability,
+            clock,
+        }
+    }
+
+    pub fn stats_table(&self) -> String {
+        let sum_calls =
+            self.nr_pread_calls.get() + self.nr_pwrite_calls.get() + self.nr_sync_calls.get();
+        let stats_table = [
+            "op        calls   ".to_string(),
+            "--------- --------".to_string(),
+            format!("pread     {:8}", self.nr_pread_calls.get()),
+            format!("pwrite    {:8}", self.nr_pwrite_calls.get()),
+            format!("sync      {:8}", self.nr_sync_calls.get()),
+            "--------- -------- --------".to_string(),
+            format!("total     {sum_calls:8}"),
+        ];
+
+        stats_table.join("\n")
+    }
+
+    #[instrument(skip_all, level = Level::TRACE)]
+    fn generate_latency(&self) -> Option<turso_core::Instant> {
+        let mut rng = self.rng.borrow_mut();
+        // Chance to introduce some latency
+        rng.random_bool(self.latency_probability as f64 / 100.0)
+            .then(|| {
+                let now = self.clock.now();
+                let sum = now + std::time::Duration::from_millis(rng.random_range(5..20));
+                sum.into()
+            })
+    }
+}
+
+impl File for MemorySimFile {
+    fn lock_file(&self, _exclusive: bool) -> Result<()> {
+        Ok(())
+    }
+
+    fn unlock_file(&self) -> Result<()> {
+        Ok(())
+    }
+
+    fn pread(&self, pos: usize, c: Completion) -> Result<Completion> {
+        self.nr_pread_calls.set(self.nr_pread_calls.get() + 1);
+
+        let op = OperationType::Read {
+            fd: self.fd.clone(),
+            completion: c.clone(),
+            offset: pos,
+        };
+        self.callbacks.lock().push(Operation {
+            time: self.generate_latency(),
+            op,
+        });
+        Ok(c)
+    }
+
+    fn pwrite(
+        &self,
+        pos: usize,
+        buffer: Arc<turso_core::Buffer>,
+        c: Completion,
+    ) -> Result<Completion> {
+        self.nr_pwrite_calls.set(self.nr_pwrite_calls.get() + 1);
+        let op = OperationType::Write {
+            fd: self.fd.clone(),
+            buffer,
+            completion: c.clone(),
+            offset: pos,
+        };
+        self.callbacks.lock().push(Operation {
+            time: self.generate_latency(),
+            op,
+        });
+        Ok(c)
+    }
+
+    fn sync(&self, c: Completion) -> Result<Completion> {
+        self.nr_sync_calls.set(self.nr_sync_calls.get() + 1);
+        let op = OperationType::Sync {
+            fd: self.fd.clone(),
+            completion: c.clone(),
+        };
+        self.callbacks.lock().push(Operation {
+            time: self.generate_latency(),
+            op,
+        });
+        Ok(c)
+    }
+
+    fn size(&self) -> Result<u64> {
+        // TODO: size operation should also be scheduled. But this requires a change in how we
+        // Use this function internally in Turso
+        Ok(self.buffer.borrow().len() as u64)
+    }
+
+    fn truncate(&self, len: usize, c: Completion) -> Result<Completion> {
+        todo!()
+    }
+}
diff --git a/simulator/runner/memory/io.rs b/simulator/runner/memory/io.rs
new file mode 100644
index 000000000..ad614ba9c
--- /dev/null
+++ b/simulator/runner/memory/io.rs
@@ -0,0 +1,253 @@
+use std::cell::{Cell, RefCell};
+use std::sync::Arc;
+
+use indexmap::IndexMap;
+use parking_lot::Mutex;
+use rand::{RngCore, SeedableRng};
+use rand_chacha::ChaCha8Rng;
+use turso_core::{Clock, Completion, Instant, OpenFlags, Result, IO};
+
+use crate::runner::clock::SimulatorClock;
+use crate::runner::SimIO;
+use crate::{model::FAULT_ERROR_MSG, runner::memory::file::MemorySimFile};
+
+/// File descriptor
+pub type Fd = String;
+
+pub enum OperationType {
+    Read {
+        fd: Arc<Fd>,
+        completion: Completion,
+        offset: usize,
+    },
+    Write {
+        fd: Arc<Fd>,
+        buffer: Arc<turso_core::Buffer>,
+        completion: Completion,
+        offset: usize,
+    },
+    Sync {
+        fd: Arc<Fd>,
+        completion: Completion,
+    },
+}
+
+impl OperationType {
+    fn get_fd(&self) -> &Fd {
+        match self {
+            OperationType::Read { fd, .. }
+            | OperationType::Write { fd, .. }
+            | OperationType::Sync { fd, .. } => fd,
+        }
+    }
+}
+
+pub struct Operation {
+    pub time: Option<turso_core::Instant>,
+    pub op: OperationType,
+}
+
+impl Operation {
+    fn do_operation(self, files: &IndexMap<Fd, Arc<MemorySimFile>>) {
+        match self.op {
+            OperationType::Read {
+                fd,
+                completion,
+                offset,
+            } => {
+                let file = files.get(fd.as_str()).unwrap();
+                let file_buf = file.buffer.borrow_mut();
+                let buffer = completion.as_read().buf.clone();
+                let buf_size = {
+                    let buf = buffer.as_mut_slice();
+                    // TODO: check for sector faults here
+
+                    buf.copy_from_slice(&file_buf[offset..][0..buf.len()]);
+                    buf.len() as i32
+                };
+                completion.complete(buf_size);
+            }
+            OperationType::Write {
+                fd,
+                buffer,
+                completion,
+                offset,
+            } => {
+                let file = files.get(fd.as_str()).unwrap();
+                let buf_size = {
+                    let mut file_buf = file.buffer.borrow_mut();
+                    let buf = buffer.as_slice();
+                    let more_space = if file_buf.len() < offset {
+                        (offset + buf.len()) - file_buf.len()
+                    } else {
+                        buf.len().saturating_sub(file_buf.len() - offset)
+                    };
+                    if more_space > 0 {
+                        file_buf.reserve(more_space);
+                        for _ in 0..more_space {
+                            file_buf.push(0);
+                        }
+                    }
+
+                    file_buf[offset..][0..buf.len()].copy_from_slice(buf);
+                    buf.len() as i32
+                };
+                completion.complete(buf_size);
+            }
+            OperationType::Sync { completion, .. } => {
+                // There is no Sync for in memory
+                completion.complete(0);
+            }
+        }
+    }
+}
+
+pub type CallbackQueue = Arc<Mutex<Vec<Operation>>>;
+
+pub struct MemorySimIO {
+    callbacks: CallbackQueue,
+    timeouts: CallbackQueue,
+    pub fault: Cell<bool>,
+    pub files: RefCell<IndexMap<Fd, Arc<MemorySimFile>>>,
+    pub rng: RefCell<ChaCha8Rng>,
+    pub nr_run_once_faults: Cell<usize>,
+    pub page_size: usize,
+    seed: u64,
+    latency_probability: usize,
+    clock: Arc<SimulatorClock>,
+}
+
+unsafe impl Send for MemorySimIO {}
+unsafe impl Sync for MemorySimIO {}
+
+impl MemorySimIO {
+    pub fn new(
+        seed: u64,
+        page_size: usize,
+        latency_probability: usize,
+        min_tick: u64,
+        max_tick: u64,
+    ) -> Result<Self> {
+        let fault = Cell::new(false);
+        let files = RefCell::new(IndexMap::new());
+        let rng = RefCell::new(ChaCha8Rng::seed_from_u64(seed));
+        let nr_run_once_faults = Cell::new(0);
+        Ok(Self {
+            callbacks: Arc::new(Mutex::new(Vec::new())),
+            timeouts: Arc::new(Mutex::new(Vec::new())),
+            fault,
+            files,
+            rng,
+            nr_run_once_faults,
+            page_size,
+            seed,
+            latency_probability,
+            clock: Arc::new(SimulatorClock::new(
+                ChaCha8Rng::seed_from_u64(seed),
+                min_tick,
+                max_tick,
+            )),
+        })
+    }
+}
+
+impl SimIO for MemorySimIO {
+    fn inject_fault(&self, fault: bool) {
+        self.fault.replace(fault);
+        if fault {
+            tracing::debug!("fault injected");
+        }
+    }
+
+    fn print_stats(&self) {
+        tracing::info!("run_once faults: {}", self.nr_run_once_faults.get());
+        for file in self.files.borrow().values() {
+            tracing::info!("\n===========================\n{}", file.stats_table());
+        }
+    }
+
+    fn syncing(&self) -> bool {
+        let callbacks = self.callbacks.try_lock().unwrap();
+        callbacks
+            .iter()
+            .any(|operation| matches!(operation.op, OperationType::Sync { .. }))
+    }
+
+    fn close_files(&self) {
+        for file in self.files.borrow().values() {
+            file.closed.set(true);
+        }
+    }
+}
+
+impl Clock for MemorySimIO {
+    fn now(&self) -> Instant {
+        self.clock.now().into()
+    }
+}
+
+impl IO for MemorySimIO {
+    fn open_file(
+        &self,
+        path: &str,
+        _flags: OpenFlags, // TODO: ignoring open flags for now as we don't test read only mode in the simulator yet
+        _direct: bool,
+    ) -> Result<Arc<dyn turso_core::File>> {
+        let mut files = self.files.borrow_mut();
+        let fd = path.to_string();
+        let file = if let Some(file) = files.get(path) {
+            file.closed.set(false);
+            file.clone()
+        } else {
+            let file = Arc::new(MemorySimFile::new(
+                self.callbacks.clone(),
+                fd.clone(),
+                self.seed,
+                self.latency_probability,
+                self.clock.clone(),
+            ));
+            files.insert(fd, file.clone());
+            file
+        };
+
+        Ok(file)
+    }
+
+    fn run_once(&self) -> Result<()> {
+        let mut callbacks = self.callbacks.lock();
+        let mut timeouts = self.timeouts.lock();
+        tracing::trace!(
+            callbacks.len = callbacks.len(),
+            timeouts.len = timeouts.len()
+        );
+        if self.fault.get() {
+            self.nr_run_once_faults
+                .replace(self.nr_run_once_faults.get() + 1);
+            // TODO: currently we only deal with single threaded execution in one file
+            // When we support multiple db files, we need to only remove callbacks not relevant to the current file
+            // and maybe connection
+            callbacks.clear();
+            timeouts.clear();
+            return Err(turso_core::LimboError::InternalError(
+                FAULT_ERROR_MSG.into(),
+            ));
+        }
+        let files = self.files.borrow_mut();
+        let now = self.now();
+
+        callbacks.append(&mut timeouts);
+
+        while let Some(callback) = callbacks.pop() {
+            if callback.time.is_none() || callback.time.is_some_and(|time| time < now) {
+                callback.do_operation(&files);
+            } else {
+                timeouts.push(callback);
+            }
+        }
+        Ok(())
+    }
+
+    fn generate_random_number(&self) -> i64 {
+        self.rng.borrow_mut().next_u64() as i64
+    }
+}
diff --git a/simulator/runner/memory/mod.rs b/simulator/runner/memory/mod.rs
new file mode 100644
index 000000000..d8e462011
--- /dev/null
+++ b/simulator/runner/memory/mod.rs
@@ -0,0 +1,2 @@
+pub mod file;
+pub mod io;
diff --git a/simulator/runner/mod.rs b/simulator/runner/mod.rs
index 13b5c4258..b729045f0 100644
--- a/simulator/runner/mod.rs
+++ b/simulator/runner/mod.rs
@@ -8,6 +8,7 @@ pub mod execution;
 #[allow(dead_code)]
 pub mod file;
 pub mod io;
+pub mod memory;
 pub mod watch;
 
 pub const FAULT_ERROR_MSG: &str = "Injected Fault";