diff --git a/Cargo.lock b/Cargo.lock
index c4c3461..4b3ecee 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -17,6 +17,12 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "anstyle"
+version = "1.0.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "038dfcf04a5feb68e9c60b21c9625a54c2c0616e79b72b0fd87075a056ae1d1b"
+
 [[package]]
 name = "anyhow"
 version = "1.0.86"
@@ -63,6 +69,12 @@ version = "0.22.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "72b3254f16251a8381aa12e40e3c4d2f0199f8c6508fbecb9d91f575e0fbb8c6"
 
+[[package]]
+name = "bitflags"
+version = "2.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b048fb63fd8b5923fc5aa7b340d8e156aec7ec02f0c78fa8a6ddc2613f6f71de"
+
 [[package]]
 name = "cc"
 version = "1.1.5"
@@ -75,6 +87,46 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
+[[package]]
+name = "clap"
+version = "4.5.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "64acc1846d54c1fe936a78dc189c34e28d3f5afc348403f28ecf53660b9b8462"
+dependencies = [
+ "clap_builder",
+ "clap_derive",
+]
+
+[[package]]
+name = "clap_builder"
+version = "4.5.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6fb8393d67ba2e7bfaf28a23458e4e2b543cc73a99595511eb207fdb8aede942"
+dependencies = [
+ "anstyle",
+ "clap_lex",
+ "strsim",
+ "terminal_size",
+]
+
+[[package]]
+name = "clap_derive"
+version = "4.5.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2bac35c6dafb060fd4d275d9a4ffae97917c13a6327903a8be2153cd964f7085"
+dependencies = [
+ "heck",
+ "proc-macro2",
+ "quote",
+ "syn 2.0.71",
+]
+
+[[package]]
+name = "clap_lex"
+version = "0.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4b82cf0babdbd58558212896d1a4272303a57bdb245c2bf1147185fb45640e70"
+
 [[package]]
 name = "collection_literals"
 version = "1.0.1"
@@ -111,6 +163,22 @@ dependencies = [
  "syn 2.0.71",
 ]
 
+[[package]]
+name = "equivalent"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5443807d6dff69373d433ab9ef5378ad8df50ca6298caf15de6e52e24aaf54d5"
+
+[[package]]
+name = "errno"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "534c5cf6194dfab3db3242765c03bbe257cf92f22b38f6bc0c58d59108a820ba"
+dependencies = [
+ "libc",
+ "windows-sys 0.52.0",
+]
+
 [[package]]
 name = "flate2"
 version = "1.0.30"
@@ -167,6 +235,18 @@ version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d2fabcfbdc87f4758337ca535fb41a6d701b65693ce38287d856d1674551ec9b"
 
+[[package]]
+name = "hashbrown"
+version = "0.14.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e5274423e17b7c9fc20b6e7e208532f9b19825d82dfd615708b70edd83df41f1"
+
+[[package]]
+name = "heck"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2304e00983f87ffb38b55b444b5e3b60a884b5d30c0fca7d82fe33449bbe55ea"
+
 [[package]]
 name = "idna"
 version = "0.5.0"
@@ -177,6 +257,16 @@ dependencies = [
  "unicode-normalization",
 ]
 
+[[package]]
+name = "indexmap"
+version = "2.2.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "168fb715dda47215e360912c096649d23d58bf392ac62f73919e831745e40f26"
+dependencies = [
+ "equivalent",
+ "hashbrown",
+]
+
 [[package]]
 name = "interpolator"
 version = "0.5.0"
@@ -195,6 +285,12 @@ version = "0.2.155"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "97b3888a4aecf77e811145cadf6eef5901f4782c53886191b2f693f24761847c"
 
+[[package]]
+name = "linux-raw-sys"
+version = "0.4.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78b3ae25bc7c8c38cec158d1f2757ee79e9b3740fbc7ccf0e59e4b08d793fa89"
+
 [[package]]
 name = "log"
 version = "0.4.22"
@@ -207,6 +303,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "assert_matches",
+ "clap",
  "get-size",
  "rstest",
  "serde",
@@ -215,6 +312,7 @@ dependencies = [
  "thousands",
  "time",
  "ureq",
+ "url",
 ]
 
 [[package]]
@@ -379,7 +477,7 @@ dependencies = [
  "libc",
  "spin",
  "untrusted",
- "windows-sys",
+ "windows-sys 0.52.0",
 ]
 
 [[package]]
@@ -418,6 +516,19 @@ dependencies = [
  "semver",
 ]
 
+[[package]]
+name = "rustix"
+version = "0.38.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "70dc5ec042f7a43c4a73241207cecc9873a06d45debb38b329f8541d85c2730f"
+dependencies = [
+ "bitflags",
+ "errno",
+ "libc",
+ "linux-raw-sys",
+ "windows-sys 0.52.0",
+]
+
 [[package]]
 name = "rustls"
 version = "0.23.11"
@@ -488,6 +599,7 @@ version = "1.0.120"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4e0d21c9a8cae1235ad58a00c11cb40d4b1e5c784f1ef2c537876ed6ffd8b7c5"
 dependencies = [
+ "indexmap",
  "itoa",
  "ryu",
  "serde",
@@ -505,6 +617,12 @@ version = "0.9.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6980e8d7511241f8acf4aebddbb1ff938df5eebe98691418c4468d0b72a96a67"
 
+[[package]]
+name = "strsim"
+version = "0.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7da8b5736845d9f2fcb837ea5d9e2628564b3b043a70948a3f0b778838c5fb4f"
+
 [[package]]
 name = "subtle"
 version = "2.6.1"
@@ -532,6 +650,16 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "terminal_size"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "21bebf2b7c9e0a515f6e0f8c51dc0f8e4696391e6f1ff30379559f8365fb0df7"
+dependencies = [
+ "rustix",
+ "windows-sys 0.48.0",
+]
+
 [[package]]
 name = "thiserror"
 version = "1.0.62"
@@ -655,6 +783,7 @@ dependencies = [
  "form_urlencoded",
  "idna",
  "percent-encoding",
+ "serde",
 ]
 
 [[package]]
@@ -678,13 +807,37 @@ dependencies = [
  "rustls-pki-types",
 ]
 
+[[package]]
+name = "windows-sys"
+version = "0.48.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "677d2418bec65e3338edb076e806bc1ec15693c5d0104683f2efe857f61056a9"
+dependencies = [
+ "windows-targets 0.48.5",
+]
+
 [[package]]
 name = "windows-sys"
 version = "0.52.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "282be5f36a8ce781fad8c8ae18fa3f9beff57ec1b52cb3de0789201425d9a33d"
 dependencies = [
- "windows-targets",
+ "windows-targets 0.52.6",
+]
+
+[[package]]
+name = "windows-targets"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a2fa6e2155d7247be68c096456083145c183cbbbc2764150dda45a87197940c"
+dependencies = [
+ "windows_aarch64_gnullvm 0.48.5",
+ "windows_aarch64_msvc 0.48.5",
+ "windows_i686_gnu 0.48.5",
+ "windows_i686_msvc 0.48.5",
+ "windows_x86_64_gnu 0.48.5",
+ "windows_x86_64_gnullvm 0.48.5",
+ "windows_x86_64_msvc 0.48.5",
 ]
 
 [[package]]
@@ -693,28 +846,46 @@ version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
 dependencies = [
- "windows_aarch64_gnullvm",
- "windows_aarch64_msvc",
- "windows_i686_gnu",
+ "windows_aarch64_gnullvm 0.52.6",
+ "windows_aarch64_msvc 0.52.6",
+ "windows_i686_gnu 0.52.6",
  "windows_i686_gnullvm",
- "windows_i686_msvc",
- "windows_x86_64_gnu",
- "windows_x86_64_gnullvm",
- "windows_x86_64_msvc",
+ "windows_i686_msvc 0.52.6",
+ "windows_x86_64_gnu 0.52.6",
+ "windows_x86_64_gnullvm 0.52.6",
+ "windows_x86_64_msvc 0.52.6",
 ]
 
+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2b38e32f0abccf9987a4e3079dfb67dcd799fb61361e53e2882c3cbaf0d905d8"
+
 [[package]]
 name = "windows_aarch64_gnullvm"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
 
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc35310971f3b2dbbf3f0690a219f40e2d9afcf64f9ab7cc1be722937c26b4bc"
+
 [[package]]
 name = "windows_aarch64_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
 
+[[package]]
+name = "windows_i686_gnu"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a75915e7def60c94dcef72200b9a8e58e5091744960da64ec734a6c6e9b3743e"
+
 [[package]]
 name = "windows_i686_gnu"
 version = "0.52.6"
@@ -727,24 +898,48 @@ version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
 
+[[package]]
+name = "windows_i686_msvc"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f55c233f70c4b27f66c523580f78f1004e8b5a8b659e05a4eb49d4166cca406"
+
 [[package]]
 name = "windows_i686_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
 
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "53d40abd2583d23e4718fddf1ebec84dbff8381c07cae67ff7768bbf19c6718e"
+
 [[package]]
 name = "windows_x86_64_gnu"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
 
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0b7b52767868a23d5bab768e390dc5f5c55825b6d30b86c844ff2dc7414044cc"
+
 [[package]]
 name = "windows_x86_64_gnullvm"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
 
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ed94fce61571a4006852b7389a063ab983c02eb1bb37b47f8272ce92d06d9538"
+
 [[package]]
 name = "windows_x86_64_msvc"
 version = "0.52.6"
diff --git a/Cargo.toml b/Cargo.toml
index 947a498..160cacb 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,7 +2,7 @@
 name = "manifest-size"
 version = "0.1.0"
 edition = "2021"
-rust-version = "1.67"
+rust-version = "1.74"
 description = "Calculate bytes consumed by Zarr manifests"
 authors = ["John Thorvald Wodder II <manifest-size@varonathe.org>"]
 repository = "https://github.com/jwodder/manifest-size"
@@ -13,13 +13,15 @@ publish = false
 
 [dependencies]
 anyhow = "1.0.86"
+clap = { version = "4.3.24", default-features = false, features = ["derive", "error-context", "help", "std", "suggestions", "usage", "wrap_help"] }
 get-size = { version = "0.1.4", features = ["derive"] }
 serde = { version = "1.0.204", features = ["derive"] }
-serde_json = "1.0.120"
+serde_json = { version = "1.0.120", features = ["preserve_order"] }
 thiserror = "1.0.62"
 thousands = "0.2.0"
 time = { version = "0.3.36", features = ["parsing", "serde"] }
 ureq = "2.10.0"
+url = { version = "2.5.2", features = ["serde"] }
 
 [dev-dependencies]
 assert_matches = "1.5.0"
diff --git a/README.md b/README.md
index 1f982b4..b3a8dd1 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,5 @@
 [![Project Status: Concept – Minimal or no implementation has been done yet, or the repository is only intended to be a limited example, demo, or proof-of-concept.](https://www.repostatus.org/badges/latest/concept.svg)](https://www.repostatus.org/#concept)
-[![Minimum Supported Rust Version](https://img.shields.io/badge/MSRV-1.67-orange)](https://www.rust-lang.org)
+[![Minimum Supported Rust Version](https://img.shields.io/badge/MSRV-1.74-orange)](https://www.rust-lang.org)
 [![MIT License](https://img.shields.io/github/license/jwodder/nhmoon.svg)](https://opensource.org/licenses/MIT)
 
 This is a Rust utility for measuring the sizes of individual [Zarr manifests][]
@@ -29,18 +29,19 @@ with:
 Usage
 =====
 
-    manifest-size <url>
+    manifest-size [-J|--json] <url>
 
 or, if running a localized binary:
 
-    cargo run [--release] -- <url>
+    cargo run [--release] -- [-J|--json] <url>
 
-`manifest-size` takes a single argument, an HTTP(S) URL pointing to a Zarr
-manifest file.  It downloads the file, parses it, and outputs the size of the
-data before & after parsing.
+`manifest-size` takes a single positional argument, an HTTP(S) URL pointing to
+a Zarr manifest file.  It downloads the file, parses it, and outputs the size
+of the data before & after parsing.  If the `-J`/`--json` option is supplied,
+the output will be in JSON.
 
-Example
-=======
+Examples
+========
 
 ```console
 $ manifest-size https://datasets.datalad.org/dandi/zarr-manifests/zarr-manifests-v2-sorted/001/e3b/001e3b6d-26fb-463f-af28-520a25680ab4/326273bcc8730474323a66ea4e3daa49-113328--97037755426.json
@@ -48,5 +49,14 @@ Raw    response: 13 818 966 bytes
 Parsed response: 18 473 917 bytes
 ```
 
+```console
+$ manifest-size --json https://datasets.datalad.org/dandi/zarr-manifests/zarr-manifests-v2-sorted/c7e/25d/c7e25dca-4dc9-4e83-a0d7-5fee56fa8773/c23f15b26134d808b072b8c93b1eeed8-48935--29709893986.json
+{
+  "url": "https://datasets.datalad.org/dandi/zarr-manifests/zarr-manifests-v2-sorted/c7e/25d/c7e25dca-4dc9-4e83-a0d7-5fee56fa8773/c23f15b26134d808b072b8c93b1eeed8-48935--29709893986.json",
+  "raw_bytes": 5935826,
+  "parsed_bytes": 7983735
+}
+```
+
 [Zarr manifests]: https://github.com/dandi/dandidav/blob/main/doc/zarrman.md
 [`dandidav`]: https://github.com/dandi/dandidav
diff --git a/src/main.rs b/src/main.rs
index cbdf710..6b294fa 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,27 +5,54 @@ mod component;
 mod manifest;
 use crate::manifest::Manifest;
 use anyhow::Context;
+use clap::Parser;
 use get_size::GetSize;
 use std::io::Read;
 use thousands::Separable;
+use url::Url;
+
+/// Display the raw & parsed sizes of a Zarr manifest
+///
+/// See <https://github.com/jwodder/manifest-size> for more information.
+#[derive(Clone, Debug, Eq, Parser, PartialEq)]
+struct Arguments {
+    /// Output JSON
+    #[arg(short = 'J', long)]
+    json: bool,
+
+    /// An HTTP(S) URL pointing to a Zarr manifest file
+    url: Url,
+}
 
 fn main() -> anyhow::Result<()> {
-    let Some(url) = std::env::args().nth(1) else {
-        anyhow::bail!("No URL argument supplied");
-    };
-    let mut r = ureq::get(&url)
+    let args = Arguments::parse();
+    let mut r = ureq::get(args.url.as_str())
         .call()
         .context("GET request failed")?
         .into_reader();
     let mut body = Vec::new();
     r.read_to_end(&mut body)
         .context("failed to read response body")?;
-    let body_len_str = body.len().separate_with_spaces();
+    let body_len = body.len();
     let parsed =
         serde_json::from_slice::<Manifest>(&body).context("failed to deserialize response")?;
-    let parsed_size_str = parsed.get_size().separate_with_spaces();
-    let width = body_len_str.len().max(parsed_size_str.len());
-    println!("Raw    response: {body_len_str:>width$} bytes");
-    println!("Parsed response: {parsed_size_str:>width$} bytes");
+    let parsed_size = parsed.get_size();
+    drop(parsed);
+    if args.json {
+        println!(
+            "{:#}",
+            serde_json::json!({
+                "url": args.url,
+                "raw_bytes": body_len,
+                "parsed_bytes": parsed_size,
+            })
+        );
+    } else {
+        let body_len_str = body_len.separate_with_spaces();
+        let parsed_size_str = parsed_size.separate_with_spaces();
+        let width = body_len_str.len().max(parsed_size_str.len());
+        println!("Raw    response: {body_len_str:>width$} bytes");
+        println!("Parsed response: {parsed_size_str:>width$} bytes");
+    }
     Ok(())
 }