diff --git a/Cargo.toml b/Cargo.toml
index 3ca20de..3f29f09 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -40,3 +40,4 @@ seq-macro = "0.3.6"
 bytesize = { version = "2.0.1", features = ["serde"] }
 bytes = { version = "1.10.1", features = ["serde"] }
 url = { version = "2.5.4", features = ["serde"] }
+blake3 = "1.8.2"
diff --git a/macros/src/str.rs b/macros/src/str.rs
index 83313c6..6f71161 100644
--- a/macros/src/str.rs
+++ b/macros/src/str.rs
@@ -52,13 +52,22 @@ pub fn transform(args: TokenStream, body: TokenStream) -> TokenStream {
                     bounds: syn::parse_quote!(#eva::str::FixedUtf8),
                 };
                 let predicate = syn::WherePredicate::Type(predicate);
-                if let Some(ref mut clause) = generics.where_clause {
+                let clause = if let Some(ref mut clause) = generics.where_clause {
                     clause.predicates.push(predicate);
+                    clause
                 } else {
                     generics.where_clause = Some(syn::parse_quote! {
                         where #predicate
                     });
-                }
+                    generics.where_clause.as_mut().unwrap()
+                };
+
+                clause.predicates.push(syn::WherePredicate::Type(syn::PredicateType {
+                    lifetimes: None,
+                    bounded_ty: error_ty.clone(),
+                    colon_token: Token![:](proc_macro2::Span::mixed_site()),
+                    bounds: syn::parse_quote!(::std::convert::From<<#ty as ::std::str::FromStr>::Err>),
+                }));
             }
 
             let (ig, tyg, where_clause) = generics.split_for_impl();
diff --git a/src/collections.rs b/src/collections.rs
index f140c5f..3c3f9e7 100644
--- a/src/collections.rs
+++ b/src/collections.rs
@@ -2,5 +2,5 @@ pub use hashbrown::{Equivalent, HashTable, hash_map, hash_table};
 
 use std::hash::BuildHasherDefault;
 
-pub type HashMap<K, V> = hashbrown::HashMap<K, V, BuildHasherDefault<crate::hash::Hasher>>;
-pub type HashSet<V> = hashbrown::HashSet<V, BuildHasherDefault<crate::hash::Hasher>>;
+pub type HashMap<K, V> = hashbrown::HashMap<K, V, BuildHasherDefault<crate::hash::U64Hasher>>;
+pub type HashSet<V> = hashbrown::HashSet<V, BuildHasherDefault<crate::hash::U64Hasher>>;
diff --git a/src/hash.rs b/src/hash.rs
index 4708cac..15dcd43 100644
--- a/src/hash.rs
+++ b/src/hash.rs
@@ -1 +1,183 @@
-pub type Hasher = ahash::AHasher;
+use std::{borrow::Cow, fmt, marker::PhantomData, mem, str::FromStr};
+
+use perfect_derive::perfect_derive;
+use schemars::JsonSchema;
+use serde::{Deserialize, Serialize};
+
+use crate::{
+    error::shit_happens,
+    int, single_ascii_char, str,
+    str::{HasPattern, ParseError, PhantomDataStr, Seq},
+};
+
+pub mod blake3;
+
+pub type U64Hasher = ahash::AHasher;
+
+#[int(u8, b'0'..=b'9' | b'A'..=b'Z' | b'a'..=b'z', crate = crate)]
+pub enum HexChar {}
+
+single_ascii_char!(HexChar);
+unsafe impl str::FixedUtf8 for HexChar {}
+
+/// Hexadecimal representation of the hash.
+#[str(fixed(error = ParseError), crate = crate)]
+pub struct Hex<IH: IsHash, const SIZE: usize> {
+    buf: Seq<SIZE, Seq<2, HexChar>>,
+    _marker: PhantomDataStr<IH>,
+}
+
+impl<IH: IsHash, const SIZE: usize> Hex<IH, SIZE> {
+    pub const fn parse(self) -> Hash<IH, SIZE> {
+        const fn hexc(c: u8) -> u8 {
+            match c.to_ascii_uppercase() {
+                b'0'..=b'9' => c - b'0',
+                b'A'..=b'F' => 10 + c - b'A',
+                _ => shit_happens(),
+            }
+        }
+
+        let mut out = [0_u8; SIZE];
+        let mut offset = 0_usize;
+
+        while offset < SIZE {
+            let [upper, lower] = self.buf.0[offset].0;
+            let upper = hexc(upper.into_inner());
+            let lower = hexc(lower.into_inner());
+
+            out[offset] = (upper << 4) | lower;
+            offset += 1;
+        }
+
+        Hash::new(out)
+    }
+}
+
+pub trait State {
+    fn update(&mut self, buf: &[u8]);
+}
+
+#[perfect_derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Hash<IH: IsHash, const SIZE: usize> {
+    buf: [u8; SIZE],
+    _marker: PhantomData<[IH; 0]>,
+}
+
+impl<IH: IsHash, const SIZE: usize> fmt::Display for Hash<IH, SIZE> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(self.hex().as_str())
+    }
+}
+
+impl<IH: IsHash, const SIZE: usize> JsonSchema for Hash<IH, SIZE> {
+    fn schema_id() -> Cow<'static, str> {
+        format!("{}::{}", module_path!(), Self::schema_name()).into()
+    }
+
+    fn schema_name() -> Cow<'static, str> {
+        format!("Hash_{}__{}", IH::schema_name(), SIZE).into()
+    }
+
+    fn json_schema(generator: &mut schemars::SchemaGenerator) -> schemars::Schema {
+        _ = generator;
+
+        schemars::json_schema!({"anyOf": [
+            {
+                "type": "string",
+                "description": format!("Hexadecimal representation of {} hash, only in human-readable formats", IH::schema_name()),
+                "minLength": SIZE * 2,
+                "maxLength": SIZE * 2,
+                "pattern": <Hex<IH, SIZE>>::regex_pat_fullmatch(),
+            },
+            {"type": "array", "minItems": SIZE, "maxItems": SIZE, "items": {
+                "type": "integer",
+                "minimum": 0,
+                "maximum": 20
+            }}
+        ]})
+    }
+}
+
+impl<'de, IH: IsHash, const SIZE: usize> Deserialize<'de> for Hash<IH, SIZE>
+where
+    [u8; SIZE]: Deserialize<'de>,
+{
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        if deserializer.is_human_readable() {
+            let hex = Hex::deserialize(deserializer)?;
+            Ok(hex.parse())
+        } else {
+            let buf = <[u8; SIZE] as Deserialize<'de>>::deserialize(deserializer)?;
+            Ok(Self {
+                buf,
+                _marker: PhantomData,
+            })
+        }
+    }
+}
+
+impl<IH: IsHash, const SIZE: usize> Serialize for Hash<IH, SIZE> {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        if serializer.is_human_readable() {
+            self.hex().serialize(serializer)
+        } else {
+            self.buf.serialize(serializer)
+        }
+    }
+}
+
+impl<IH: IsHash, const SIZE: usize> FromStr for Hash<IH, SIZE> {
+    type Err = ParseError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Hex::from_str(s).map(|h| h.parse())
+    }
+}
+
+impl<IH: IsHash, const SIZE: usize> Hash<IH, SIZE> {
+    pub const fn new(buf: [u8; SIZE]) -> Self {
+        Self {
+            buf,
+            _marker: PhantomData,
+        }
+    }
+
+    pub const fn hex(&self) -> Hex<IH, SIZE> {
+        const fn hexc(c: u8) -> u8 {
+            match c {
+                0..=9 => b'0' + c,
+                10..=15 => b'a' + (c - 10),
+                _ => shit_happens(),
+            }
+        }
+        let mut out: [[u8; 2]; SIZE] = [[0, 0]; SIZE];
+        let mut offset = 0_usize;
+
+        while offset < SIZE {
+            let num = self.buf[offset];
+            let [upper, lower] = &mut out[offset];
+            *upper = hexc(num >> 4);
+            *lower = hexc(num & 0b1111);
+
+            offset += 1;
+        }
+
+        Hex {
+            buf: unsafe { mem::transmute_copy(&out) },
+            _marker: PhantomDataStr(PhantomData),
+        }
+    }
+}
+
+pub trait IsHash: JsonSchema + Copy + 'static + Send + Sync + Ord {
+    const FULL_SIZE: usize;
+}
+
+#[cfg(test)]
+mod tests;
diff --git a/src/hash/blake3.rs b/src/hash/blake3.rs
new file mode 100644
index 0000000..4d4f6e1
--- /dev/null
+++ b/src/hash/blake3.rs
@@ -0,0 +1,32 @@
+use crate::hash::{self, IsHash, State};
+
+pub const FULL_SIZE: usize = 32;
+pub type Hash = hash::Hash<Blake3, FULL_SIZE>;
+
+#[derive(Debug, Clone, Default)]
+pub struct Hasher(blake3::Hasher);
+
+impl Hasher {
+    pub fn finish(&self) -> Hash {
+        let h = self.0.finalize();
+        Hash::new(*h.as_bytes())
+    }
+}
+
+impl State for Hasher {
+    fn update(&mut self, buf: &[u8]) {
+        self.0.update(buf);
+    }
+}
+
+#[crate::data(copy, ord, crate = crate)]
+pub enum Blake3 {}
+
+impl IsHash for Blake3 {
+    const FULL_SIZE: usize = FULL_SIZE;
+}
+
+pub fn hash(bytes: &[u8]) -> Hash {
+    let h = blake3::hash(bytes);
+    Hash::new(*h.as_bytes())
+}
diff --git a/src/hash/tests.rs b/src/hash/tests.rs
new file mode 100644
index 0000000..caf98fe
--- /dev/null
+++ b/src/hash/tests.rs
@@ -0,0 +1,11 @@
+use crate::hash::blake3;
+
+#[test]
+fn blake3_from_str_and_back_identical() {
+    const STR: &str = "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff";
+
+    let h: blake3::Hash = STR.parse().unwrap();
+    let hex = h.hex();
+
+    assert_eq!(hex.as_str(), STR);
+}
diff --git a/src/str.rs b/src/str.rs
index a313c80..842ecd6 100644
--- a/src/str.rs
+++ b/src/str.rs
@@ -1,8 +1,9 @@
-use std::{fmt, mem::MaybeUninit, slice, str::FromStr};
+use std::{fmt, marker::PhantomData, mem::MaybeUninit, slice, str::FromStr};
 
 pub use compact_str::{
     CompactString, CompactStringExt, ToCompactString, ToCompactStringError, format_compact,
 };
+use perfect_derive::perfect_derive;
 
 use crate::data;
 
@@ -35,6 +36,30 @@ macro_rules! single_ascii_char {
     };
 }
 
+#[perfect_derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[derive(serde::Serialize, serde::Deserialize, schemars::JsonSchema)]
+pub struct PhantomDataStr<C>(pub PhantomData<C>);
+
+impl<C> HasPattern for PhantomDataStr<C> {
+    #[inline]
+    fn pat_into(buf: &mut String) {
+        _ = buf;
+    }
+}
+
+unsafe impl<C> FixedUtf8 for PhantomDataStr<C> {}
+impl<C> FromStr for PhantomDataStr<C> {
+    type Err = ParseError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        if s.is_empty() {
+            Ok(Self(PhantomData))
+        } else {
+            Err(ParseError::Length)
+        }
+    }
+}
+
 /// Simple parse error.
 #[data(copy, error, display(doc), crate = crate)]
 pub enum ParseError {