diff --git a/Cargo.lock b/Cargo.lock
index c0e30e7c5..02a32e182 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -132,6 +132,15 @@ dependencies = [
  "num-traits",
 ]
 
+[[package]]
+name = "arbitrary"
+version = "1.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dde20b3d026af13f561bdd0f15edf01fc734f0dafcedbaf42bba506a9517f223"
+dependencies = [
+ "derive_arbitrary",
+]
+
 [[package]]
 name = "arrayvec"
 version = "0.5.2"
@@ -717,6 +726,17 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "derive_arbitrary"
+version = "1.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "30542c1ad912e0e3d22a1935c290e12e8a29d704a420177a31faad4a601a0800"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "derive_more"
 version = "0.99.20"
@@ -1027,6 +1047,14 @@ dependencies = [
  "slab",
 ]
 
+[[package]]
+name = "fuzz"
+version = "0.0.0"
+dependencies = [
+ "hugr-model",
+ "libfuzzer-sys",
+]
+
 [[package]]
 name = "fxhash"
 version = "0.2.1"
@@ -1303,6 +1331,7 @@ dependencies = [
 name = "hugr-model"
 version = "0.20.2"
 dependencies = [
+ "arbitrary",
  "base64",
  "bumpalo",
  "capnp",
@@ -1796,6 +1825,16 @@ version = "0.2.173"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d8cfeafaffdbc32176b64fb251369d52ea9f0a8fbc6f8759edffef7b525d64bb"
 
+[[package]]
+name = "libfuzzer-sys"
+version = "0.4.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf78f52d400cf2d84a3a973a78a592b4adc535739e0a5597a0da6f0c357adc75"
+dependencies = [
+ "arbitrary",
+ "cc",
+]
+
 [[package]]
 name = "linux-raw-sys"
 version = "0.9.4"
@@ -2006,6 +2045,7 @@ version = "5.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e2c1f9f56e534ac6a9b8a4600bdf0f530fb393b5f393e7b4d03489c3cf0c3f01"
 dependencies = [
+ "arbitrary",
  "num-traits",
  "rand 0.8.5",
  "serde",
@@ -2912,6 +2952,7 @@ version = "0.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9676b89cd56310a87b93dec47b11af744f34d5fc9f367b829474eec0a891350d"
 dependencies = [
+ "arbitrary",
  "borsh",
  "serde",
 ]
diff --git a/Cargo.toml b/Cargo.toml
index b1ffa4de0..3aaa91880 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -4,14 +4,15 @@ lto = "thin"
 [workspace]
 resolver = "2"
 members = [
-    "hugr",
-    "hugr-core",
-    "hugr-passes",
-    "hugr-cli",
-    "hugr-model",
-    "hugr-llvm",
-    "hugr-py",
-    "hugr-persistent",
+  "hugr",
+  "hugr-core",
+  "hugr-passes",
+  "hugr-cli",
+  "hugr-model",
+  "hugr-llvm",
+  "hugr-py",
+  "hugr-persistent",
+  "fuzz",
 ]
 default-members = ["hugr", "hugr-core", "hugr-passes", "hugr-cli", "hugr-model"]
 
@@ -25,10 +26,10 @@ license = "Apache-2.0"
 
 [workspace.lints.rust]
 unexpected_cfgs = { level = "warn", check-cfg = [
-    # Set by our CI
-    'cfg(ci_run)',
-    # Set by codecov
-    'cfg(coverage,coverage_nightly)',
+  # Set by our CI
+  'cfg(ci_run)',
+  # Set by codecov
+  'cfg(coverage,coverage_nightly)',
 ] }
 
 missing_docs = "warn"
diff --git a/devenv.lock b/devenv.lock
index 9b13193f5..92626f0c5 100644
--- a/devenv.lock
+++ b/devenv.lock
@@ -51,31 +51,10 @@
         "type": "github"
       }
     },
-    "git-hooks": {
-      "inputs": {
-        "flake-compat": "flake-compat",
-        "gitignore": "gitignore",
-        "nixpkgs": [
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1747372754,
-        "owner": "cachix",
-        "repo": "git-hooks.nix",
-        "rev": "80479b6ec16fefd9c1db3ea13aeb038c60530f46",
-        "type": "github"
-      },
-      "original": {
-        "owner": "cachix",
-        "repo": "git-hooks.nix",
-        "type": "github"
-      }
-    },
     "gitignore": {
       "inputs": {
         "nixpkgs": [
-          "git-hooks",
+          "pre-commit-hooks",
           "nixpkgs"
         ]
       },
@@ -107,15 +86,33 @@
         "type": "github"
       }
     },
+    "pre-commit-hooks": {
+      "inputs": {
+        "flake-compat": "flake-compat",
+        "gitignore": "gitignore",
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1747372754,
+        "owner": "cachix",
+        "repo": "pre-commit-hooks.nix",
+        "rev": "80479b6ec16fefd9c1db3ea13aeb038c60530f46",
+        "type": "github"
+      },
+      "original": {
+        "owner": "cachix",
+        "repo": "pre-commit-hooks.nix",
+        "type": "github"
+      }
+    },
     "root": {
       "inputs": {
         "devenv": "devenv",
         "fenix": "fenix",
-        "git-hooks": "git-hooks",
         "nixpkgs": "nixpkgs",
-        "pre-commit-hooks": [
-          "git-hooks"
-        ]
+        "pre-commit-hooks": "pre-commit-hooks"
       }
     },
     "rust-analyzer-src": {
diff --git a/devenv.nix b/devenv.nix
index 8664a43d3..d17c3b483 100644
--- a/devenv.nix
+++ b/devenv.nix
@@ -48,7 +48,7 @@ in
     # https://devenv.sh/languages/
     # https://devenv.sh/reference/options/#languagesrustversion
     languages.rust = {
-      channel = "stable";
+      channel = "nightly";
       enable = true;
       components = [ "rustc" "cargo" "clippy" "rustfmt" "rust-analyzer" ];
     };
diff --git a/fuzz/Cargo.toml b/fuzz/Cargo.toml
new file mode 100644
index 000000000..524b25fce
--- /dev/null
+++ b/fuzz/Cargo.toml
@@ -0,0 +1,29 @@
+[package]
+name = "fuzz"
+version = "0.0.0"
+publish = false
+edition = "2024"
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies]
+libfuzzer-sys = "0.4"
+hugr-model = { path = "../hugr-model/", features = ["arbitrary"] }
+
+# [dependencies.hugr]
+# path = ".."
+
+[[bin]]
+name = "fuzz_random"
+path = "fuzz_targets/fuzz_random.rs"
+test = false
+doc = false
+bench = false
+
+[[bin]]
+name = "fuzz_structure"
+path = "fuzz_targets/fuzz_structure.rs"
+test = false
+doc = false
+bench = false
diff --git a/fuzz/README.md b/fuzz/README.md
new file mode 100644
index 000000000..68b9fc1c4
--- /dev/null
+++ b/fuzz/README.md
@@ -0,0 +1,64 @@
+# Fuzz testing
+
+This project uses `cargo-fuzz` for doing fuzz testing for hugr.
+
+## Requisites
+
+1. Install `cargo-fuzz` with: `cargo install cargo-fuzz`
+2. Build with `cargo fuzz build`
+
+> [!NOTE]
+> The `libFuzzer` used by `cargo-fuzz` needs **nightly**.
+
+## Fuzz targets
+
+You can list the fuzzing targets with:
+`cargo fuzz list`
+
+### Model: Random
+
+The [fuzz_random](./fuzz_targets/fuzz_random.rs) target uses the coverage-guided
+`libFuzzer` fuzzing engine to generate random bytes that we then try to
+convert to a package with `hugr_model::v0::ast::Package::from_str()`.
+
+To run this target:
+`cargo fuzz run fuzz_random`
+
+It is recommended to provide the `libFuzzer` with a corpus to speed up the
+generation of test inputs. For this we can use the fixtures in
+`hugr/hugr-model/tests/fixtures`:
+`cargo fuzz run fuzz_random ../hugr-model/tests/fixtures`
+
+If you want `libFuzzer` to mutate the examples with ascii characters only:
+`cargo fuzz run fuzz_random -- -only_ascii=1`
+
+### Model: Structure
+
+The [fuzz_structure](./fuzz_targets/fuzz_structure.rs) target uses `libFuzzer` to do
+[structure-aware](https://rust-fuzz.github.io/book/cargo-fuzz/structure-aware-fuzzing.html)
+modifications of the `hugr_model::v0::ast::Package` and its members.
+
+To run this target:
+`cargo fuzz run fuzz_structure`
+
+> [!NOTE]
+> This target needs some slight modifications to the `hugr-model` source
+> code so the structs and enums can derive the `Arbitrary` implementations
+> needed by `libFuzzer`.
+> The `arbitrary` features for `ordered-float` and `smol_str` are also needed.
+
+## Results
+
+The fuzzing process will be terminated once a crash is detected, and the offending input
+will be saved to the `artifacts/<target>` directory. You can reproduce the crash by doing:
+`cargo fuzz run fuzz_structure artifacts/<target>/crash-XXXXXX`
+
+If you want to keep the fuzzing process, even after a crash has been detected,
+you can provide the options `-fork=1` and `-ignore_crashes=1`.
+
+## Providing options to `libFuzzer`
+
+You can provide lots of options to `libFuzzer` by doing `cargo fuzz run <target> -- -flag1=val1 -flag2=val2`.
+
+To see all the available options:
+`cargo fuzz run <target> -- -help=1`
diff --git a/fuzz/fuzz_targets/fuzz_random.rs b/fuzz/fuzz_targets/fuzz_random.rs
new file mode 100644
index 000000000..866e5405f
--- /dev/null
+++ b/fuzz/fuzz_targets/fuzz_random.rs
@@ -0,0 +1,11 @@
+#![no_main]
+
+use libfuzzer_sys::fuzz_target;
+use hugr_model::v0 as model;
+use std::str::FromStr;
+
+fuzz_target!(|data: &[u8]| {
+    if let Ok(s) = std::str::from_utf8(data) {
+        let _package_ast = model::ast::Package::from_str(&s);
+    }
+});
diff --git a/fuzz/fuzz_targets/fuzz_structure.rs b/fuzz/fuzz_targets/fuzz_structure.rs
new file mode 100644
index 000000000..ec0882c56
--- /dev/null
+++ b/fuzz/fuzz_targets/fuzz_structure.rs
@@ -0,0 +1,14 @@
+#![no_main]
+
+use hugr_model::v0 as model;
+use libfuzzer_sys::fuzz_target;
+use model::bumpalo::Bump;
+use hugr_model::v0::ast::Package;
+
+fuzz_target!(|package: Package| {
+    let bump = Bump::new();
+    let package = package.resolve(&bump).unwrap();
+    let bytes = model::binary::write_to_vec(&package);
+    let deserialized_package = model::binary::read_from_slice(&bytes, &bump).unwrap();
+    assert_eq!(package, deserialized_package);
+});
diff --git a/hugr-model/Cargo.toml b/hugr-model/Cargo.toml
index 24c1f9e42..11863687b 100644
--- a/hugr-model/Cargo.toml
+++ b/hugr-model/Cargo.toml
@@ -23,13 +23,14 @@ derive_more = { workspace = true, features = ["display", "error", "from"] }
 fxhash.workspace = true
 indexmap.workspace = true
 itertools.workspace = true
-ordered-float = { workspace = true }
+ordered-float = { workspace = true, features = ["arbitrary"] }
 pest = { workspace = true }
 pest_derive = { workspace = true }
 pretty = { workspace = true }
-smol_str = { workspace = true, features = ["serde"] }
+smol_str = { workspace = true, features = ["serde", "arbitrary"] }
 thiserror.workspace = true
 pyo3 = { workspace = true, optional = true, features = ["extension-module"] }
+arbitrary = { version = "1", optional = true, features = ["derive"] }
 
 [features]
 pyo3 = ["dep:pyo3"]
diff --git a/hugr-model/src/v0/ast/mod.rs b/hugr-model/src/v0/ast/mod.rs
index faee6f827..1b44c02ba 100644
--- a/hugr-model/src/v0/ast/mod.rs
+++ b/hugr-model/src/v0/ast/mod.rs
@@ -43,6 +43,7 @@ pub use resolve::ResolveError;
 ///
 /// [`table::Package`]: crate::v0::table::Package
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature="arbitrary", derive(arbitrary::Arbitrary))]
 pub struct Package {
     /// The sequence of modules in the package.
     pub modules: Vec<Module>,
@@ -70,6 +71,7 @@ impl Package {
 ///
 /// [`table::Module`]: crate::v0::table::Module
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature="arbitrary", derive(arbitrary::Arbitrary))]
 pub struct Module {
     /// The root region of the module.
     ///
@@ -103,6 +105,7 @@ impl Module {
 ///
 /// [`table::Node`]: crate::v0::table::Node
 #[derive(Debug, Clone, PartialEq, Eq, Default)]
+#[cfg_attr(feature="arbitrary", derive(arbitrary::Arbitrary))]
 pub struct Node {
     /// The operation that the node performs.
     pub operation: Operation,
@@ -129,6 +132,7 @@ pub struct Node {
 ///
 /// [`table::Operation`]: crate::v0::table::Operation
 #[derive(Debug, Clone, PartialEq, Eq, Default)]
+#[cfg_attr(feature="arbitrary", derive(arbitrary::Arbitrary))]
 pub enum Operation {
     /// Invalid operation to be used as a placeholder.
     #[default]
@@ -193,6 +197,7 @@ impl Operation {
 ///
 /// [`table::Symbol`]: crate::v0::table::Symbol
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature="arbitrary", derive(arbitrary::Arbitrary))]
 pub struct Symbol {
     /// The name of the symbol.
     pub name: SymbolName,
@@ -210,6 +215,7 @@ pub struct Symbol {
 ///
 /// [`table::Param`]: crate::v0::table::Param
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature="arbitrary", derive(arbitrary::Arbitrary))]
 pub struct Param {
     /// The name of the parameter.
     pub name: VarName,
@@ -223,6 +229,7 @@ pub struct Param {
 ///
 /// [`table::Region`]: crate::v0::table::Region
 #[derive(Debug, Clone, PartialEq, Eq, Default)]
+#[cfg_attr(feature="arbitrary", derive(arbitrary::Arbitrary))]
 pub struct Region {
     /// The kind of the region. See [`RegionKind`] for details.
     pub kind: RegionKind,
@@ -247,6 +254,7 @@ pub struct Region {
 ///
 /// [`table::Term`]: crate::v0::table::Term
 #[derive(Debug, Clone, PartialEq, Eq, Default)]
+#[cfg_attr(feature="arbitrary", derive(arbitrary::Arbitrary))]
 pub enum Term {
     /// Standin for any term.
     #[default]
@@ -277,6 +285,7 @@ impl From<Literal> for Term {
 ///
 /// [`table::SeqPart`]: crate::v0::table::SeqPart
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature="arbitrary", derive(arbitrary::Arbitrary))]
 pub enum SeqPart {
     /// An individual item in the sequence.
     Item(Term),
diff --git a/hugr-model/src/v0/mod.rs b/hugr-model/src/v0/mod.rs
index 27e6605ae..59d9f946c 100644
--- a/hugr-model/src/v0/mod.rs
+++ b/hugr-model/src/v0/mod.rs
@@ -343,6 +343,7 @@ impl<'py> pyo3::IntoPyObject<'py> for ScopeClosure {
 
 /// The kind of a region.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Default)]
+#[cfg_attr(feature="arbitrary", derive(arbitrary::Arbitrary))]
 pub enum RegionKind {
     /// Data flow region.
     #[default]
@@ -388,6 +389,7 @@ impl<'py> pyo3::IntoPyObject<'py> for RegionKind {
 
 /// The name of a variable.
 #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[cfg_attr(feature="arbitrary", derive(arbitrary::Arbitrary))]
 pub struct VarName(SmolStr);
 
 impl VarName {
@@ -424,6 +426,7 @@ impl<'py> pyo3::IntoPyObject<'py> for &VarName {
 
 /// The name of a symbol.
 #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[cfg_attr(feature="arbitrary", derive(arbitrary::Arbitrary))]
 pub struct SymbolName(SmolStr);
 
 impl SymbolName {
@@ -449,6 +452,7 @@ impl<'py> pyo3::FromPyObject<'py> for SymbolName {
 
 /// The name of a link.
 #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[cfg_attr(feature="arbitrary", derive(arbitrary::Arbitrary))]
 pub struct LinkName(SmolStr);
 
 impl LinkName {
@@ -496,6 +500,7 @@ impl<'py> pyo3::IntoPyObject<'py> for &LinkName {
 /// sequences of arbitrary length. To enable cheap cloning and sharing,
 /// strings and byte sequences use reference counting.
 #[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[cfg_attr(feature="arbitrary", derive(arbitrary::Arbitrary))]
 pub enum Literal {
     /// String literal.
     Str(SmolStr),