diff --git a/Cargo.lock b/Cargo.lock
index 164c974..c1ec355 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -74,7 +74,7 @@ checksum = "965c2d33e53cb6b267e148a4cb0760bc01f4904c1cd4bb4002a085bb016d1490"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
  "synstructure",
 ]
 
@@ -86,7 +86,7 @@ checksum = "3109e49b1e4909e9db6515a30c633684d68cdeaa252f215214cb4fa1a5bfee2c"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
  "synstructure",
 ]
 
@@ -98,7 +98,7 @@ checksum = "7b18050c2cd6fe86c3a76584ef5e0baf286d038cda203eb6223df2cc413565f7"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
 ]
 
 [[package]]
@@ -109,7 +109,7 @@ checksum = "9035ad2d096bed7955a320ee7e2230574d28fd3c3a0f186cbea1ff3c7eed5dbb"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
 ]
 
 [[package]]
@@ -130,6 +130,15 @@ version = "2.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "812e12b5285cc515a9c72a5c1d3b6d46a19dac5acfef5265968c166106e31dd3"
 
+[[package]]
+name = "block-buffer"
+version = "0.10.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3078c7629b62d3f0439517fa394996acacc5cbc91c5a20d8c658e77abd503a71"
+dependencies = [
+ "generic-array",
+]
+
 [[package]]
 name = "boa_ast"
 version = "0.20.0"
@@ -227,7 +236,7 @@ checksum = "9fd3f870829131332587f607a7ff909f1af5fc523fd1b192db55fbbdf52e8d3c"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
  "synstructure",
 ]
 
@@ -292,7 +301,7 @@ checksum = "f9abbd1bc6865053c427f7198e6af43bfdedc55ab791faed4fbd361d789575ff"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
 ]
 
 [[package]]
@@ -346,6 +355,15 @@ dependencies = [
  "unicode-segmentation",
 ]
 
+[[package]]
+name = "cpufeatures"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "59ed5838eebb26a2bb2e58f6d5b5316989ae9d08bab10e0e6d103e656d1b0280"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "crossbeam-utils"
 version = "0.8.21"
@@ -358,6 +376,16 @@ version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "460fbee9c2c2f33933d720630a6a0bac33ba7053db5344fac858d4b8952d77d5"
 
+[[package]]
+name = "crypto-common"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78c8292055d1c1df0cce5d180393dc8cce0abec0a7102adb6c7b1eef6016d60a"
+dependencies = [
+ "generic-array",
+ "typenum",
+]
+
 [[package]]
 name = "ctor"
 version = "0.6.2"
@@ -431,6 +459,16 @@ dependencies = [
  "powerfmt",
 ]
 
+[[package]]
+name = "digest"
+version = "0.10.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9ed9a281f7bc9b7576e61468ba615a66a5c8cfdff42420a70aa82701a3b1e292"
+dependencies = [
+ "block-buffer",
+ "crypto-common",
+]
+
 [[package]]
 name = "displaydoc"
 version = "0.2.5"
@@ -439,7 +477,7 @@ checksum = "97369cbbc041bc366949bc74d34658d6cda5621039731c6310521892a3a20ae0"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
 ]
 
 [[package]]
@@ -449,14 +487,17 @@ dependencies = [
  "anyhow",
  "boa_engine",
  "droplet-rs",
+ "format-bytes",
+ "hashing-reader",
  "hex",
- "md5",
+ "humansize",
  "napi",
  "napi-build",
  "napi-derive",
  "rhai",
  "serde",
  "serde_json",
+ "sha2",
  "tokio",
  "tokio-util",
  "uuid",
@@ -537,6 +578,26 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "77ce24cb58228fbb8aa041425bb1050850ac19177686ea6e0f41a70416f56fdb"
 
+[[package]]
+name = "format-bytes"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "48942366ef93975da38e175ac9e10068c6fc08ca9e85930d4f098f4d5b14c2fd"
+dependencies = [
+ "format-bytes-macros",
+]
+
+[[package]]
+name = "format-bytes-macros"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "203aadebefcc73d12038296c228eabf830f99cba991b0032adf20e9fa6ce7e4f"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 1.0.109",
+]
+
 [[package]]
 name = "futures"
 version = "0.3.31"
@@ -593,7 +654,7 @@ checksum = "162ee34ebcb7c64a8abebc059ce0fee27c2262618d7b60ed8faf72fef13c3650"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
 ]
 
 [[package]]
@@ -626,6 +687,16 @@ dependencies = [
  "slab",
 ]
 
+[[package]]
+name = "generic-array"
+version = "0.14.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85649ca51fd72272d7821adaf274ad91c288277713d9c18820d8499a7ff69e9a"
+dependencies = [
+ "typenum",
+ "version_check",
+]
+
 [[package]]
 name = "getrandom"
 version = "0.2.16"
@@ -677,12 +748,32 @@ dependencies = [
  "foldhash 0.2.0",
 ]
 
+[[package]]
+name = "hashing-reader"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "490b80ea8c6d700506827951d7196fede236081b9c976a42b30598fa77377d15"
+dependencies = [
+ "digest",
+ "pin-project",
+ "tokio",
+]
+
 [[package]]
 name = "hex"
 version = "0.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
 
+[[package]]
+name = "humansize"
+version = "2.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6cb51c9a029ddc91b07a787f1d86b53ccfa49b0e86688c946ebe8d3555685dd7"
+dependencies = [
+ "libm",
+]
+
 [[package]]
 name = "icu_collections"
 version = "1.5.0"
@@ -798,7 +889,7 @@ checksum = "1ec89e9337638ecdc08744df490b221a7399bf8d164eb52a665454e60e075ad6"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
 ]
 
 [[package]]
@@ -876,6 +967,12 @@ dependencies = [
  "windows-link",
 ]
 
+[[package]]
+name = "libm"
+version = "0.2.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f9fbbcab51052fe104eb5e5d351cf728d30a5be1fe14d9be8a3b097481fb97de"
+
 [[package]]
 name = "litemap"
 version = "0.7.5"
@@ -891,12 +988,6 @@ dependencies = [
  "scopeguard",
 ]
 
-[[package]]
-name = "md5"
-version = "0.7.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "490cc448043f947bae3cbee9c203358d62dbee0db12107a74be5c30ccfd09771"
-
 [[package]]
 name = "memchr"
 version = "2.7.6"
@@ -965,7 +1056,7 @@ dependencies = [
  "napi-derive-backend",
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
 ]
 
 [[package]]
@@ -978,7 +1069,7 @@ dependencies = [
  "proc-macro2",
  "quote",
  "semver",
- "syn",
+ "syn 2.0.111",
 ]
 
 [[package]]
@@ -1060,7 +1151,7 @@ dependencies = [
  "proc-macro-crate",
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
 ]
 
 [[package]]
@@ -1158,7 +1249,7 @@ dependencies = [
  "phf_shared",
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
 ]
 
 [[package]]
@@ -1170,6 +1261,26 @@ dependencies = [
  "siphasher",
 ]
 
+[[package]]
+name = "pin-project"
+version = "1.1.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "677f1add503faace112b9f1373e43e9e054bfdd22ff1a63c1bc485eaec6a6a8a"
+dependencies = [
+ "pin-project-internal",
+]
+
+[[package]]
+name = "pin-project-internal"
+version = "1.1.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6e918e4ff8c4549eb882f14b3a4bc8c8bc93de829416eacf579f1207a8fbf861"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.111",
+]
+
 [[package]]
 name = "pin-project-lite"
 version = "0.2.16"
@@ -1359,7 +1470,7 @@ checksum = "d4322a2a4e8cf30771dd9f27f7f37ca9ac8fe812dddd811096a98483080dabe6"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
 ]
 
 [[package]]
@@ -1457,7 +1568,7 @@ checksum = "d540f220d3187173da220f885ab66608367b6574e925011a9353e4badda91d79"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
 ]
 
 [[package]]
@@ -1473,6 +1584,17 @@ dependencies = [
  "serde_core",
 ]
 
+[[package]]
+name = "sha2"
+version = "0.10.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a7507d819769d01a365ab707794a4084392c824f54a7a6a7862f8c3d0892b283"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "digest",
+]
+
 [[package]]
 name = "shlex"
 version = "1.3.0"
@@ -1535,6 +1657,17 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a2eb9349b6444b326872e140eb1cf5e7c522154d69e7a0ffb0fb81c06b37543f"
 
+[[package]]
+name = "syn"
+version = "1.0.109"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72b64191b275b66ffe2469e8af2c1cfe3bafa67b529ead792a6d0160888b4237"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
 [[package]]
 name = "syn"
 version = "2.0.111"
@@ -1554,7 +1687,7 @@ checksum = "728a70f3dbaf5bab7f0c4b1ac8d7ae5ea60a4b5549c8a5914361c99147a709d2"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
 ]
 
 [[package]]
@@ -1595,7 +1728,7 @@ checksum = "4fee6c4efc90059e10f81e6d42c60a18f76588c3d74cb83a0b242a2b6c7504c1"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
 ]
 
 [[package]]
@@ -1606,7 +1739,7 @@ checksum = "3ff15c8ecd7de3849db632e14d18d2571fa09dfc5ed93479bc4485c7a517c913"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
 ]
 
 [[package]]
@@ -1730,6 +1863,12 @@ dependencies = [
  "winnow",
 ]
 
+[[package]]
+name = "typenum"
+version = "1.19.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "562d481066bde0658276a35467c4af00bdc6ee726305698a55b86e61d7ad82bb"
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.22"
@@ -1781,7 +1920,7 @@ checksum = "39d11901c36b3650df7acb0f9ebe624f35b5ac4e1922ecd3c57f444648429594"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
 ]
 
 [[package]]
@@ -1837,7 +1976,7 @@ dependencies = [
  "bumpalo",
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
  "wasm-bindgen-shared",
 ]
 
@@ -2040,7 +2179,7 @@ checksum = "2380878cad4ac9aac1e2435f3eb4020e8374b5f13c296cb75b4620ff8e229154"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
  "synstructure",
 ]
 
@@ -2061,7 +2200,7 @@ checksum = "d8a8d209fdf45cf5138cbb5a506f6b52522a25afccc534d1475dad8e31105c6a"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
 ]
 
 [[package]]
@@ -2081,7 +2220,7 @@ checksum = "d71e5d6e06ab090c67b5e44993ec16b72dcbaabc526db883a360057678b48502"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
  "synstructure",
 ]
 
@@ -2110,5 +2249,5 @@ checksum = "6eafa6dfb17584ea3e2bd6e76e0cc15ad7af12b09abdd1ca55961bed9b1063c6"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn",
+ "syn 2.0.111",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index 2587e81..6635eeb 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -17,7 +17,6 @@ napi = { version = "3.0.0-beta.11", default-features = false, features = [
 ] }
 napi-derive = "3.0.0-beta.11"
 hex = "0.4.3"
-md5 = "0.7.0"
 tokio = { version = "1.45.1", features = ["fs", "io-util"] }
 tokio-util = { version = "0.7.15", features = ["codec"] }
 rhai = "1.22.2"
@@ -26,6 +25,10 @@ boa_engine = "0.20.0"
 serde_json = "1.0.143"
 anyhow = "*"
 droplet-rs = { git = "https://github.com/Drop-OSS/droplet-rs.git" }
+hashing-reader = "0.1.0"
+sha2 = "0.10.9"
+format-bytes = "0.3.0"
+humansize = "2.1.3"
 
 [dependencies.serde]
 version = "1.0.210"
diff --git a/__test__/utils.spec.mjs b/__test__/utils.spec.mjs
index 6edc2fc..6660e20 100644
--- a/__test__/utils.spec.mjs
+++ b/__test__/utils.spec.mjs
@@ -149,6 +149,9 @@ test("zip manifest test", async (t) => {
         (_, __) => {}
       )
     );
+    const files = await listFiles("./assets/" + zipFile);
+
+    if(Object.keys(manifest).length == 0) return t.fail("manifest was empty")
 
     for (const [filename, data] of Object.entries(manifest)) {
       let start = 0;
diff --git a/src/lib.rs b/src/lib.rs
index f149e46..15ee362 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -3,6 +3,7 @@
 #![deny(clippy::panic)]
 #![feature(trait_alias)]
 #![feature(iterator_try_collect)]
+#![feature(int_roundings)]
 
 
 pub mod manifest;
diff --git a/src/manifest.rs b/src/manifest.rs
index a623b8f..28e87d0 100644
--- a/src/manifest.rs
+++ b/src/manifest.rs
@@ -1,23 +1,36 @@
 use std::{collections::HashMap, sync::Arc, thread};
 
+use droplet_rs::versions::types::VersionFile;
+use hashing_reader::HashingReader;
+use hex::ToHex;
+use humansize::{format_size, BINARY};
 use napi::{
   threadsafe_function::{ThreadsafeFunction, ThreadsafeFunctionCallMode},
   Result,
 };
+use serde::Serialize;
 use serde_json::json;
+use sha2::{Digest, Sha256};
 use tokio::io::AsyncReadExt as _;
 use uuid::Uuid;
 
 use crate::version::create_backend_for_path;
 
-const CHUNK_SIZE: usize = 1024 * 1024 * 64;
+const CHUNK_SIZE: u64 = 1024 * 1024 * 64;
+const WIGGLE: u64 = 1024 * 1024 * 1;
 
-#[derive(serde::Serialize)]
-struct ChunkData {
+#[derive(Serialize)]
+struct FileEntry {
+  filename: String,
+  start: usize,
+  length: usize,
   permissions: u32,
-  ids: Vec<String>,
-  checksums: Vec<String>,
-  lengths: Vec<usize>,
+}
+
+#[derive(Serialize)]
+struct ChunkData {
+  files: Vec<FileEntry>,
+  checksum: String,
 }
 
 #[napi]
@@ -29,89 +42,185 @@ pub fn call_alt_thread_func(tsfn: Arc<ThreadsafeFunction<()>>) -> Result<(), Str
   Ok(())
 }
 
+#[derive(Serialize)]
+struct Manifest {
+  version: String,
+  chunks: HashMap<String, ChunkData>,
+  size: u64,
+}
+
 #[napi]
-pub async fn generate_manifest<'a>(
+pub async fn generate_manifest(
   dir: String,
-  progress_sfn: ThreadsafeFunction<i32>,
+  progress_sfn: ThreadsafeFunction<f32>,
   log_sfn: ThreadsafeFunction<String>,
 ) -> anyhow::Result<String> {
   let mut backend = create_backend_for_path(dir).ok_or(napi::Error::from_reason(
     "Could not create backend for path.",
   ))?;
 
-  let required_single_file = backend.require_whole_files();
+  let required_single_file = true; //backend.require_whole_files();
 
-  let files = backend.list_files().await?;
+  let mut files = backend.list_files().await?;
   // Filepath to chunk data
-  let mut chunks: HashMap<String, ChunkData> = HashMap::new();
+  let mut chunks: Vec<Vec<(VersionFile, u64, u64)>> = Vec::new();
+  let mut current_chunk: Vec<(VersionFile, u64, u64)> = Vec::new();
 
-  let total: i32 = files.len() as i32;
-  let mut i: i32 = 0;
-
-  let mut buf = [0u8; 1024 * 16];
+  log_sfn.call(
+    Ok(format!("organizing files into chunks...",)),
+    ThreadsafeFunctionCallMode::NonBlocking,
+  );
 
   for version_file in files {
-    let mut reader = backend.reader(&version_file, 0, 0).await?;
+    //    let mut reader = backend.reader(&version_file, 0, 0).await?;
 
-    let mut chunk_data = ChunkData {
-      permissions: version_file.permission,
-      ids: Vec::new(),
-      checksums: Vec::new(),
-      lengths: Vec::new(),
-    };
+    // If we need the whole file, and this file would take up a whole chunk, add it to it's own chunk and move on
+    if required_single_file && version_file.size >= CHUNK_SIZE {
+      let size = version_file.size;
+      chunks.push(vec![(version_file, 0, size)]);
 
-    let mut chunk_index = 0;
-    loop {
-      let mut length = 0;
-      let mut buffer: Vec<u8> = Vec::new();
-      let mut file_empty = false;
-
-      loop {
-        let read = reader.read(&mut buf).await?;
-
-        length += read;
-
-        // If we're out of data, add this chunk and then move onto the next file
-        if read == 0 {
-          file_empty = true;
-          break;
-        }
-
-        buffer.extend_from_slice(&buf[0..read]);
-
-        if length >= CHUNK_SIZE && !required_single_file {
-          break;
-        }
-      }
-
-      let chunk_id = Uuid::new_v4();
-      let checksum = md5::compute(buffer).0;
-      let checksum_string = hex::encode(checksum);
-
-      chunk_data.ids.push(chunk_id.to_string());
-      chunk_data.checksums.push(checksum_string);
-      chunk_data.lengths.push(length);
-
-      let log_str = format!(
-        "Processed chunk {} for {}",
-        chunk_index, &version_file.relative_filename
-      );
-
-      log_sfn.call(Ok(log_str), ThreadsafeFunctionCallMode::Blocking);
-
-      chunk_index += 1;
-
-      if file_empty {
-        break;
-      }
+      continue;
     }
 
-    chunks.insert(version_file.relative_filename, chunk_data);
+    let mut current_size = current_chunk.iter().map(|v| v.2 - v.1).sum::<u64>();
 
-    i += 1;
-    let progress = i * 100 / total;
+    // If we need the whole file, add this current file and move on, potentially adding and creating new chunk if need be
+    if required_single_file {
+      let size = version_file.size.try_into().unwrap();
+      current_chunk.push((version_file, 0, size));
+
+      current_size += size;
+
+      if current_size >= CHUNK_SIZE {
+        // Pop current and add, then reset
+        let new_chunk = std::mem::replace(&mut current_chunk, Vec::new());
+        chunks.push(new_chunk);
+      }
+
+      continue;
+    }
+
+    // Otherwise we calculate how much of the file we need, then use that much
+    let remaining_budget = (CHUNK_SIZE + WIGGLE) - current_size;
+    if version_file.size >= remaining_budget {
+      let remaining_budget = CHUNK_SIZE - current_size;
+      current_chunk.push((version_file.clone(), 0, remaining_budget));
+
+      let new_chunk = std::mem::replace(&mut current_chunk, Vec::new());
+      chunks.push(new_chunk);
+
+      let remaining_size = version_file.size - remaining_budget;
+      let mut running_offset = remaining_budget;
+      // Do everything but the last one
+      while running_offset < remaining_size {
+        let chunk_size = CHUNK_SIZE.min(remaining_size);
+        let chunk = vec![(version_file.clone(), running_offset, chunk_size)];
+        if chunk_size == CHUNK_SIZE {
+          chunks.push(chunk);
+        } else {
+          current_chunk = chunk;
+        }
+        running_offset += chunk_size;
+      }
+
+      continue;
+    } else {
+      let size = version_file.size;
+      current_chunk.push((version_file, 0, size));
+      current_size += size;
+    }
+
+    if current_size >= CHUNK_SIZE {
+      // Pop current and add, then reset
+      let new_chunk = std::mem::replace(&mut current_chunk, Vec::new());
+      chunks.push(new_chunk);
+    }
+  }
+  if current_chunk.len() > 0 {
+    chunks.push(current_chunk);
+  }
+
+  log_sfn.call(
+    Ok(format!(
+      "organized into {} chunks, generating checksums...",
+      chunks.len()
+    )),
+    ThreadsafeFunctionCallMode::Blocking,
+  );
+
+  let mut manifest: HashMap<String, ChunkData> = HashMap::new();
+  let mut total_manifest_length = 0;
+
+  let mut read_buf = vec![0; 1024 * 1024 * 64];
+
+  let chunk_len = chunks.len();
+  for (index, chunk) in chunks.into_iter().enumerate() {
+    let uuid = uuid::Uuid::new_v4().to_string();
+    let mut hasher = Sha256::new();
+
+    let mut chunk_data = ChunkData {
+      files: Vec::new(),
+      checksum: String::new(),
+    };
+
+    let mut chunk_length = 0;
+
+    for (file, start, length) in chunk {
+      log_sfn.call(
+        Ok(format!(
+          "reading {} from {} to {}, {}",
+          file.relative_filename,
+          start,
+          start + length,
+          format_size(length, BINARY)
+        )),
+        ThreadsafeFunctionCallMode::Blocking,
+      );
+      let mut reader = backend.reader(&file, start, start + length).await?;
+
+      loop {
+        let amount = reader.read(&mut read_buf).await?;
+        if amount == 0 {
+          break;
+        }
+        hasher.update(&read_buf[0..amount]);
+      }
+
+      chunk_length += length;
+
+      chunk_data.files.push(FileEntry {
+        filename: file.relative_filename,
+        start: start.try_into().unwrap(),
+        length: length.try_into().unwrap(),
+        permissions: file.permission,
+      });
+    }
+
+    log_sfn.call(
+      Ok(format!(
+        "created chunk of size {} ({}/{})",
+        format_size(chunk_length, BINARY),
+        index,
+        chunk_len
+      )),
+      ThreadsafeFunctionCallMode::Blocking,
+    );
+    total_manifest_length += chunk_length;
+
+    let hash: String = hasher.finalize().encode_hex();
+    chunk_data.checksum = hash;
+    manifest.insert(uuid, chunk_data);
+
+    let progress: f32 = (index as f32 / chunk_len as f32) * 100.0f32;
     progress_sfn.call(Ok(progress), ThreadsafeFunctionCallMode::Blocking);
   }
 
-  Ok(json!(chunks).to_string())
+  Ok(
+    json!(Manifest {
+      version: "2".to_string(),
+      chunks: manifest,
+      size: total_manifest_length
+    })
+    .to_string(),
+  )
 }
diff --git a/test.js b/test.js
new file mode 100644
index 0000000..9c1ec9f
--- /dev/null
+++ b/test.js
@@ -0,0 +1,7 @@
+const droplet = require('.');
+const fs = require('fs');
+
+(async () => {
+    const manifest = await droplet.generateManifest("/home/decduck/Games/STAR WARS Jedi Survivor", console.log, console.log);
+    fs.writeFileSync('./manifest.json', manifest);
+})();