diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 46445d2..f14237e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -40,7 +40,7 @@ jobs:
         python-version: ${{ matrix.python-version }}
 
     - name: Install package
-      run: python -m pip install .[test]
+      run: python -m pip install .[test,schema]
 
     - name: Test
       run: python -m pytest -ra
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 8847338..8c6796d 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -39,7 +39,6 @@ repos:
         - importlib_metadata
         - importlib_resources
 
-
   - repo: https://github.com/pre-commit/pygrep-hooks
     rev: v1.10.0
     hooks:
@@ -72,3 +71,9 @@ repos:
     hooks:
       - id: check-readthedocs
       - id: check-github-workflows
+      - id: check-metaschema
+        files: ^src/uhi/resources/histogram.json$
+      - id: check-jsonschema
+        name: Validate Histogram examples
+        args: [--schemafile, src/uhi/resources/histogram.json]
+        files: ^tests/resources/.*\.json
diff --git a/docs/conf.py b/docs/conf.py
index 9c5a56a..6fd87d6 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -32,6 +32,7 @@
 # ones.
 extensions = [
     "myst_parser",
+    "sphinx-jsonschema",
     "sphinx.ext.napoleon",
     "sphinx_copybutton",
     "sphinx_github_changelog",
diff --git a/docs/index.rst b/docs/index.rst
index 55cc258..4a9dfd6 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -30,6 +30,7 @@ to plot a histogram, including error bars.
    indexing.rst
    indexing+.rst
    plotting.rst
+   serialization.md
    changelog.md
 
 
diff --git a/docs/serialization.md b/docs/serialization.md
new file mode 100644
index 0000000..cd2bddf
--- /dev/null
+++ b/docs/serialization.md
@@ -0,0 +1,118 @@
+# Serialization
+
+
+## Introduction
+
+Histogram serialization has to cover a wide range of formats. As such, we
+describe a form for serialization that covers the metadata structure as
+JSON-like, with a provided JSON-schema. The data (bins and/or variable edges)
+is stored out-of-band in a binary format based on what type of data file you
+are in.  For very small (primarily 1D) histograms, data is allowed inline as
+well.
+
+The following formats are being targeted:
+
+```
+┌────────┐ ┌────────┐ ┌───────┐
+│  ROOT  │ │  HDF5  │ │  ZIP  │
+└────────┘ └────────┘ └───────┘
+```
+
+Other formats can be used as well, assuming they support out-of-band data and
+text attributes or files for the metadata.
+
+## Caveats
+
+This structure was based heavily on boost-histogram, but it is intended to be
+general, and can be expanded in the future as needed. As such, the following
+limitations are required:
+
+* Serialization followed by deserialisation may cause axis changes. Axis types
+  may change to an equivalent but less performant axis, growth status will be
+  lost, etc.
+* Metadata must be expressible as JSON. It should also be reasonably sized; some
+  formats like HDF5 may limit the size of attributes to 64K.
+* Floating point errors could be incurred on conversion, as the storage format
+  uses a stable but different representation.
+* Axis `name` is only part of the metadata, and is not standardized. This is
+  due to lack of support from boost-histogram.
+
+## Design
+
+The following axes types are supported:
+
+* `"regular"`: A regularly spaced set of even bins. Boost-histogram's "integer"
+  axes maps to this axis as well. Has `upper`, `lower`, `bins`, `underflow`,
+  `overflow`, and `circular` properties. `circular` defaults to False if not
+  present.
+* `"variable"`: A continuous axis defined by bins+1 edges. Has `edges`, which
+  is either an in-line list of numbers or a string pointing to an out-of-band data source.
+  Also has `underflow`, `overflow`, and `circular` properties. `circular`
+  defaults to False if not present.
+* `"category_int"`: A list of integer bins, non-continuous. Has `categories`,
+  which is an in-line list of integers. Also has `flow`.
+* `"category_str"`: A list of string bins. Has `categories`,
+  which is an in-line list of strings. Also has `flow`.
+* `"boolean"`: A true/false axis.
+
+Axes with gaps are currently not supported.
+
+All axes support `metadata`, a string-valued dictionary of arbitrary, JSON-like data.
+
+The following storages are supported:
+
+* `"int"`: A collection of integers. Boost-histogram's Int64 and AtomicInt64
+  map to this, and sometimes Unlimited.
+* `"double"`: A collection of 64-bit floating point values. Boost-histogram's
+  Double storage maps to this, and sometimes Unlimited.
+* `"weighted"`: A collection of two arrays of 64-bit floating point values,
+  `"value"` and `"variance"`. Boost-histogram's Weight storage maps to this.
+* `"mean"`: A collection of three arrays of 64-bit floating point values,
+  "count", "value", and "variance". Boost-histogram's Mean storage maps to
+  this.
+* `"weighted_mean"`: A collection of four arrays of 64-bit floating point
+  values, `"sum_of_weights"`, `"sum_of_weights_squared"`, `"values"`, and
+  `"variances"`. Boost-histogram's WeighedMean storage maps to this.
+
+## CLI/API
+
+You can currently test a JSON file against the schema by running:
+
+```console
+$ python -m uhi.schema some/file.json
+```
+
+Or with code:
+
+```python
+import uhi.schema
+
+uhi.schema.validate("some/file.json")
+```
+
+Eventually this should also be usable for JSON's inside zip, HDF5 attributes,
+and maybe more.
+
+```{warning}
+
+Currently, this spec describes **how to prepare the metadata** for one of the
+targeted backends. It does not yet cover backend specific details, like how to
+define and use the binary resource locator strings or how to store the data.
+JSON is not a target spec, but just part of the ZIP spec, meaning the files
+that currently "pass" the tool above would be valid inside a `.zip` file
+eventually, but are not valid by themselves.
+```
+
+## Rendered schema
+
+```{jsonschema} ../src/uhi/resources/histogram.json
+```
+
+
+## Full schema
+
+The full schema is below:
+
+```{literalinclude} ../src/uhi/resources/histogram.json
+:language: json
+```
diff --git a/noxfile.py b/noxfile.py
index 0f6205f..2a576a9 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -28,7 +28,7 @@ def tests(session):
     """
     Run the unit and regular tests.
     """
-    session.install("-e.[test]")
+    session.install("-e.[test,schema]")
     session.run("pytest", *session.posargs)
 
 
diff --git a/pyproject.toml b/pyproject.toml
index 1ba50a0..28173b2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -44,10 +44,15 @@ Documentation = "https://uhi.readthedocs.io/en/latest/"
 Changelog = "https://github.com/scikit-hep/uhi/releases"
 
 [project.optional-dependencies]
+schema = [
+  "fastjsonschema",
+  "importlib-resources; python_version<'3.9'",
+]
 docs = [
   "sphinx>=4.0",
   "furo",
   "sphinx-copybutton>=0.3.1",
+  "sphinx-jsonschema",
   "myst-parser",
   "sphinx_github_changelog",
 ]
@@ -88,6 +93,10 @@ show_error_codes = true
 warn_unreachable = true
 enable_error_code = ["ignore-without-code", "redundant-expr", "truthy-bool"]
 
+[[tool.mypy.overrides]]
+module = ["fastjsonschema"]
+ignore_missing_imports = true
+
 [tool.ruff]
 select = [
   "E", "F", "W", # flake8
diff --git a/src/uhi/resources/histogram.json b/src/uhi/resources/histogram.json
new file mode 100644
index 0000000..e62ecbb
--- /dev/null
+++ b/src/uhi/resources/histogram.json
@@ -0,0 +1,290 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "$id": "https://raw.githubusercontent.com/scikit-hep/uhi/henryiii/feat/schema/src/uhi/resources/histogram.json",
+  "title": "Histogram",
+  "type": "object",
+  "additionalProperties": false,
+  "patternProperties": {
+    ".+": {
+      "type": "object",
+      "required": ["axes", "storage"],
+      "additionalProperties": false,
+      "properties": {
+        "metadata": {
+          "type": "object",
+          "description": "Arbitrary metadata dictionary."
+        },
+        "axes": {
+          "type": "array",
+          "description": "A list of the axes of the histogram.",
+          "items": {
+            "oneOf": [
+              { "$ref": "#/$defs/regular_axis" },
+              { "$ref": "#/$defs/variable_axis" },
+              { "$ref": "#/$defs/category_str_axis" },
+              { "$ref": "#/$defs/category_int_axis" },
+              { "$ref": "#/$defs/boolean_axis" }
+            ]
+          }
+        },
+        "storage": {
+          "description": "The storage of the bins of the histogram.",
+          "oneOf": [
+            { "$ref": "#/$defs/int_storage" },
+            { "$ref": "#/$defs/double_storage" },
+            { "$ref": "#/$defs/weighted_storage" },
+            { "$ref": "#/$defs/mean_storage" },
+            { "$ref": "#/$defs/weighted_mean_storage" }
+          ]
+        }
+      }
+    }
+  },
+  "$defs": {
+    "regular_axis": {
+      "type": "object",
+      "description": "An evenly spaced set of continuous bins.",
+      "required": ["type", "lower", "upper", "bins", "underflow", "overflow"],
+      "additionalProperties": false,
+      "properties": {
+        "type": { "type": "string", "const": "regular" },
+        "lower": { "type": "number", "description": "Lower edge of the axis." },
+        "upper": { "type": "number", "description": "Upper edge of the axis." },
+        "bins": {
+          "type": "integer",
+          "minimum": 0,
+          "description": "Number of bins in the axis."
+        },
+        "underflow": {
+          "type": "boolean",
+          "description": "True if there is a bin for underflow."
+        },
+        "overflow": {
+          "type": "boolean",
+          "description": "True if there is a bin for overflow."
+        },
+        "circular": {
+          "type": "boolean",
+          "description": "True if the axis wraps around."
+        },
+        "metadata": {
+          "type": "object",
+          "description": "Arbitrary metadata dictionary."
+        }
+      }
+    },
+    "variable_axis": {
+      "type": "object",
+      "description": "A variably spaced set of continuous bins.",
+      "required": ["type", "edges", "underflow", "overflow"],
+      "additionalProperties": false,
+      "properties": {
+        "type": { "type": "string", "const": "variable" },
+        "edges": {
+          "oneOf": [
+            {
+              "type": "array",
+              "items": { "type": "number", "minItems": 2, "uniqueItems": true }
+            },
+            {
+              "type": "string",
+              "description": "A path (URI?) to the edges data."
+            }
+          ]
+        },
+        "underflow": { "type": "boolean" },
+        "overflow": { "type": "boolean" },
+        "circular": { "type": "boolean" },
+        "metadata": {
+          "type": "object",
+          "description": "Arbitrary metadata dictionary."
+        }
+      }
+    },
+    "category_str_axis": {
+      "type": "object",
+      "description": "A set of string categorical bins.",
+      "required": ["type", "categories", "flow"],
+      "additionalProperties": false,
+      "properties": {
+        "type": { "type": "string", "const": "category_str" },
+        "categories": {
+          "type": "array",
+          "items": { "type": "string" },
+          "uniqueItems": true
+        },
+        "flow": {
+          "type": "boolean",
+          "description": "True if flow bin (at the overflow position) present."
+        },
+        "metadata": {
+          "type": "object",
+          "description": "Arbitrary metadata dictionary."
+        }
+      }
+    },
+    "category_int_axis": {
+      "type": "object",
+      "description": "A set of integer categorical bins in any order.",
+      "required": ["type", "categories", "flow"],
+      "additionalProperties": false,
+      "properties": {
+        "type": { "type": "string", "const": "category_int" },
+        "categories": {
+          "type": "array",
+          "items": { "type": "integer" },
+          "uniqueItems": true
+        },
+        "flow": {
+          "type": "boolean",
+          "description": "True if flow bin (at the overflow position) present."
+        },
+        "metadata": {
+          "type": "object",
+          "description": "Arbitrary metadata dictionary."
+        }
+      }
+    },
+    "boolean_axis": {
+      "type": "object",
+      "description": "A simple true/false axis with no flow.",
+      "required": ["type"],
+      "additionalProperties": false,
+      "properties": {
+        "type": { "type": "string", "const": "boolean" },
+        "metadata": {
+          "type": "object",
+          "description": "Arbitrary metadata dictionary."
+        }
+      }
+    },
+    "int_storage": {
+      "type": "object",
+      "description": "A storage holding integer counts.",
+      "required": ["type", "data"],
+      "additionalProperties": false,
+      "properties": {
+        "type": { "type": "string", "const": "int" },
+        "data": {
+          "oneOf": [
+            {
+              "type": "string",
+              "description": "A path (URI?) to the integer bin data."
+            },
+            { "type": "array", "items": { "type": "integer" } }
+          ]
+        }
+      }
+    },
+    "double_storage": {
+      "type": "object",
+      "description": "A storage holding floating point counts.",
+      "required": ["type", "data"],
+      "additionalProperties": false,
+      "properties": {
+        "type": { "type": "string", "const": "double" },
+        "data": {
+          "oneOf": [
+            {
+              "type": "string",
+              "description": "A path (URI?) to the floating point bin data."
+            },
+            { "type": "array", "items": { "type": "number" } }
+          ]
+        }
+      }
+    },
+    "weighted_storage": {
+      "type": "object",
+      "description": "A storage holding floating point counts and variances.",
+      "required": ["type", "data"],
+      "additionalProperties": false,
+      "properties": {
+        "type": { "type": "string", "const": "int" },
+        "data": {
+          "oneOf": [
+            {
+              "type": "string",
+              "description": "A path (URI?) to the floating point bin data; outer dimension is [value, variance]"
+            },
+            {
+              "type": "object",
+              "required": ["values", "variances"],
+              "additionalProperties": false,
+              "properties": {
+                "values": { "type": "array", "items": { "type": "number" } },
+                "variances": { "type": "array", "items": { "type": "number" } }
+              }
+            }
+          ]
+        }
+      }
+    },
+    "mean_storage": {
+      "type": "object",
+      "description": "A storage holding 'profile'-style floating point counts, values, and variances.",
+      "required": ["type", "data"],
+      "additionalProperties": false,
+      "properties": {
+        "type": { "type": "string", "const": "int" },
+        "data": {
+          "oneOf": [
+            {
+              "type": "string",
+              "description": "A path (URI?) to the floating point bin data; outer dimension is [counts, value, variance]"
+            },
+            {
+              "type": "object",
+              "required": ["counts", "values", "variances"],
+              "additionalProperties": false,
+              "properties": {
+                "counts": { "type": "array", "items": { "type": "number" } },
+                "values": { "type": "array", "items": { "type": "number" } },
+                "variances": { "type": "array", "items": { "type": "number" } }
+              }
+            }
+          ]
+        }
+      }
+    },
+    "weighted_mean_storage": {
+      "type": "object",
+      "description": "A storage holding 'profile'-style floating point ∑weights, ∑weights², values, and variances.",
+      "required": ["type", "data"],
+      "additionalProperties": false,
+      "properties": {
+        "type": { "type": "string", "const": "int" },
+        "data": {
+          "oneOf": [
+            {
+              "type": "string",
+              "description": "A path (URI?) to the floating point bin data; outer dimension is [∑weights, ∑weights², value, variance]"
+            },
+            {
+              "type": "object",
+              "required": [
+                "sum_of_weights",
+                "sum_of_weights_squared",
+                "values",
+                "variances"
+              ],
+              "additionalProperties": false,
+              "properties": {
+                "sum_of_weights": {
+                  "type": "array",
+                  "items": { "type": "number" }
+                },
+                "sum_of_weights_squared": {
+                  "type": "array",
+                  "items": { "type": "number" }
+                },
+                "values": { "type": "array", "items": { "type": "number" } },
+                "variances": { "type": "array", "items": { "type": "number" } }
+              }
+            }
+          ]
+        }
+      }
+    }
+  }
+}
diff --git a/src/uhi/schema.py b/src/uhi/schema.py
new file mode 100644
index 0000000..3d1662e
--- /dev/null
+++ b/src/uhi/schema.py
@@ -0,0 +1,29 @@
+from __future__ import annotations
+
+import json
+import sys
+from pathlib import Path
+
+import fastjsonschema
+
+if sys.version_info < (3, 9):
+    import importlib_resources as resources
+else:
+    from importlib import resources
+
+histogram_file = resources.files("uhi") / "resources/histogram.json"
+
+with histogram_file.open(encoding="utf-8") as f:
+    histogram_schema = fastjsonschema.compile(json.load(f))
+
+
+def validate(path: str | Path) -> None:
+    path = Path(path)
+    with path.open(encoding="utf-8") as f:
+        example = json.load(f)
+
+    histogram_schema(example)
+
+
+if __name__ == "__main__":
+    validate(*sys.argv[1:])
diff --git a/tests/resources/reg.json b/tests/resources/reg.json
new file mode 100644
index 0000000..0e7643e
--- /dev/null
+++ b/tests/resources/reg.json
@@ -0,0 +1,30 @@
+{
+  "one": {
+    "metadata": {},
+    "axes": [
+      {
+        "type": "regular",
+        "lower": 0,
+        "upper": 5,
+        "bins": 3,
+        "underflow": true,
+        "overflow": true,
+        "circular": false
+      }
+    ],
+    "storage": { "type": "int", "data": [1, 2, 3, 4, 5] }
+  },
+  "two": {
+    "axes": [
+      {
+        "type": "regular",
+        "lower": 0,
+        "upper": 5,
+        "bins": 5,
+        "underflow": true,
+        "overflow": true
+      }
+    ],
+    "storage": { "type": "double", "data": "some/path/depends/on/format" }
+  }
+}
diff --git a/tests/test_histogram_schema.py b/tests/test_histogram_schema.py
new file mode 100644
index 0000000..4f02c4d
--- /dev/null
+++ b/tests/test_histogram_schema.py
@@ -0,0 +1,11 @@
+from __future__ import annotations
+
+from pathlib import Path
+
+import uhi.schema
+
+DIR = Path(__file__).parent.resolve()
+
+
+def test_example_1() -> None:
+    uhi.schema.validate(DIR / "resources/reg.json")