diff --git a/candle-wasm-examples/llama2-c/Cargo.toml b/candle-wasm-examples/llama2-c/Cargo.toml
index 6a128e19..dab99aee 100644
--- a/candle-wasm-examples/llama2-c/Cargo.toml
+++ b/candle-wasm-examples/llama2-c/Cargo.toml
@@ -12,6 +12,7 @@ license.workspace = true
 candle = { path = "../../candle-core", version = "0.1.0", package = "candle-core" }
 candle-nn = { path = "../../candle-nn", version = "0.1.0" }
 num-traits = { workspace = true }
+tokenizers = { workspace = true, features = ["unstable_wasm"] }
 
 # App crates.
 anyhow = { workspace = true }
diff --git a/candle-wasm-examples/llama2-c/index.html b/candle-wasm-examples/llama2-c/index.html
index e98e1ecb..6c8fe8ff 100644
--- a/candle-wasm-examples/llama2-c/index.html
+++ b/candle-wasm-examples/llama2-c/index.html
@@ -4,7 +4,7 @@
     <meta charset="utf-8" />
     <title>Welcome to Candle!</title>
 
-    <link data-trunk rel="copy-file" href="tokenizer.bin" />
+    <link data-trunk rel="copy-file" href="tokenizer.json" />
     <link data-trunk rel="copy-file" href="model.bin" />
     <link data-trunk rel="rust" href="Cargo.toml" data-bin="app" data-type="main" />
     <link data-trunk rel="rust" href="Cargo.toml" data-bin="worker" data-type="worker" />
diff --git a/candle-wasm-examples/llama2-c/src/app.rs b/candle-wasm-examples/llama2-c/src/app.rs
index d4ac6d07..f17cdbe3 100644
--- a/candle-wasm-examples/llama2-c/src/app.rs
+++ b/candle-wasm-examples/llama2-c/src/app.rs
@@ -53,7 +53,7 @@ pub struct App {
 }
 
 async fn model_data_load() -> Result<ModelData, JsValue> {
-    let tokenizer = fetch_url("tokenizer.bin").await?;
+    let tokenizer = fetch_url("tokenizer.json").await?;
     let model = fetch_url("model.bin").await?;
     console_log!("{}", model.len());
     Ok(ModelData { tokenizer, model })
diff --git a/candle-wasm-examples/llama2-c/src/lib.rs b/candle-wasm-examples/llama2-c/src/lib.rs
index 61154d04..b6b4004f 100644
--- a/candle-wasm-examples/llama2-c/src/lib.rs
+++ b/candle-wasm-examples/llama2-c/src/lib.rs
@@ -1,28 +1,3 @@
-#![allow(dead_code)]
-
-pub const WITH_TIMER: bool = true;
-
-struct Timer {
-    label: &'static str,
-}
-
-impl Timer {
-    fn new(label: &'static str) -> Self {
-        if WITH_TIMER {
-            web_sys::console::time_with_label(label);
-        }
-        Self { label }
-    }
-}
-
-impl Drop for Timer {
-    fn drop(&mut self) {
-        if WITH_TIMER {
-            web_sys::console::time_end_with_label(self.label)
-        }
-    }
-}
-
 mod app;
 mod model;
 mod worker;
diff --git a/candle-wasm-examples/llama2-c/src/model.rs b/candle-wasm-examples/llama2-c/src/model.rs
index 8cf53c2a..3231cabf 100644
--- a/candle-wasm-examples/llama2-c/src/model.rs
+++ b/candle-wasm-examples/llama2-c/src/model.rs
@@ -106,14 +106,15 @@ struct CausalSelfAttention {
     n_key_value_head: usize,
     head_dim: usize,
     cache: Cache,
-    max_seq_len: usize,
 }
 
 impl CausalSelfAttention {
     fn apply_rotary_emb(&self, x: &Tensor, index_pos: usize) -> Result<Tensor> {
         let (b_sz, seq_len, h, n_embd) = x.dims4()?;
-        let cos = self.cache.cos.narrow(0, index_pos, seq_len)?;
-        let sin = self.cache.sin.narrow(0, index_pos, seq_len)?;
+        let cos = self.cache.cos.i(index_pos..index_pos + seq_len)?;
+        let sin = self.cache.sin.i(index_pos..index_pos + seq_len)?;
+        let cos = cos.unsqueeze(1)?;
+        let sin = sin.unsqueeze(1)?;
         let cos = cos.broadcast_as((b_sz, seq_len, 1, n_embd / 2, 1))?;
         let sin = sin.broadcast_as((b_sz, seq_len, 1, n_embd / 2, 1))?;
         let x = x.reshape((b_sz, seq_len, h, n_embd / 2, 2))?;
@@ -196,7 +197,6 @@ impl CausalSelfAttention {
             n_key_value_head: cfg.n_kv_heads,
             head_dim: cfg.dim / cfg.n_heads,
             cache: cache.clone(),
-            max_seq_len: cfg.seq_len,
         })
     }
 }
diff --git a/candle-wasm-examples/llama2-c/src/worker.rs b/candle-wasm-examples/llama2-c/src/worker.rs
index 79f7c1fd..3a43c57a 100644
--- a/candle-wasm-examples/llama2-c/src/worker.rs
+++ b/candle-wasm-examples/llama2-c/src/worker.rs
@@ -4,6 +4,7 @@ use candle::{DType, Device, IndexOp, Result, Shape, Tensor, D};
 use candle_nn::{ops::softmax, VarBuilder};
 use rand::{distributions::Distribution, SeedableRng};
 use serde::{Deserialize, Serialize};
+use tokenizers::Tokenizer;
 use wasm_bindgen::prelude::*;
 use yew_agent::{HandlerId, Public, WorkerLink};
 
@@ -48,23 +49,6 @@ fn read_tensor<R: std::io::Read, S: Into<Shape>>(
     Ok(tensor)
 }
 
-struct Tokenizer {
-    tokens: Vec<String>,
-}
-
-impl Tokenizer {
-    fn from_reader<R: std::io::Read>(r: &mut R, c: &Config) -> Result<Self> {
-        let mut tokens = Vec::with_capacity(c.vocab_size);
-        for _token_index in 0..c.vocab_size {
-            let token_len = read_i32(r)?;
-            let mut token = vec![0u8; token_len as usize];
-            r.read_exact(&mut token)?;
-            tokens.push(String::from_utf8_lossy(&token).into_owned())
-        }
-        Ok(Self { tokens })
-    }
-}
-
 struct Model {
     cache: Cache,
     config: Config,
@@ -129,8 +113,10 @@ impl Model {
 
             let next_token = logits_processor.sample(&logits)?;
             tokens.push(next_token);
-            let token = self.tokenizer.tokens[next_token as usize].clone();
-            link.respond(id, Ok(WorkerOutput::Generated(token)));
+            if let Some(text) = self.tokenizer.id_to_token(next_token) {
+                let text = text.replace('▁', " ").replace("<0x0A>", "\n");
+                link.respond(id, Ok(WorkerOutput::Generated(text)));
+            }
         }
         Ok(())
     }
@@ -282,8 +268,8 @@ impl Model {
         let vb = weights.var_builder(&config, &dev)?;
         let cache = Cache::new(true, &config, vb.pp("rot"))?;
         let llama = Llama::load(vb, &cache, &config)?;
-        let mut tokenizer = std::io::Cursor::new(md.tokenizer);
-        let tokenizer = Tokenizer::from_reader(&mut tokenizer, &config)?;
+        let tokenizer =
+            Tokenizer::from_bytes(&md.tokenizer).map_err(|m| candle::Error::Msg(m.to_string()))?;
         Ok(Self {
             cache,
             config,