diff --git a/README.md b/README.md
index d2724b4..98b496a 100644
--- a/README.md
+++ b/README.md
@@ -54,7 +54,7 @@ ensuring that your response handling code is also correct. Examples are below.
 [![Clojars Project](https://img.shields.io/clojars/v/com.github.oliyh/martian-vcr.svg)](https://clojars.org/com.github.oliyh/martian-vcr) [![cljdoc badge](https://cljdoc.org/badge/com.github.oliyh/martian-vcr)](https://cljdoc.org/d/com.github.oliyh/martian-vcr/CURRENT)
 
 ## Features
-- Bootstrap an instance from just a OpenAPI/Swagger url or provide your own API mapping
+- Bootstrap an instance from just a OpenAPI/Swagger url, a local definition file or provide your own API mapping
 - Modular with support for [clj-http](https://github.com/dakrone/clj-http), [clj-http-lite](https://github.com/hiredman/clj-http-lite), [httpkit](https://github.com/http-kit/http-kit), [hato](https://github.com/gnarroway/hato) (Clojure), [cljs-http](https://github.com/r0man/cljs-http) and [cljs-http-promise](https://github.com/oliyh/cljs-http-promise) (ClojureScript)
 - Build urls and request maps from code or generate and perform the request, returning the response
 - Validate requests and responses to ensure they are correct before the data leaves/enters your system
@@ -127,6 +127,12 @@ like that provided by [pedestal-api](https://github.com/oliyh/pedestal-api):
                    (get-in [:body :id]))]))
 ```
 
+Note that when calling `bootstrap-openapi` you can also provide a url to a local resource, e.g. `(martian-http/bootstrap-openapi "public/openapi.json")`.
+For ClojureScript the file can only be read at compile time, so a slightly different form is required using the `martian.file/load-local-resource` macro:
+```clj
+(martian/bootstrap-openapi "https://sandbox.example.com" (load-local-resource "openapi-test.json") martian-http/default-opts)
+```
+
 ## No Swagger, no problem
 
 Although bootstrapping against a remote OpenAPI or Swagger API using `bootstrap-openapi` is simplest
diff --git a/babashka-http-client/src/martian/babashka/http_client.clj b/babashka-http-client/src/martian/babashka/http_client.clj
index 409be86..41876ff 100644
--- a/babashka-http-client/src/martian/babashka/http_client.clj
+++ b/babashka-http-client/src/martian/babashka/http_client.clj
@@ -2,6 +2,7 @@
   (:require [babashka.http-client :as http]
             [babashka.json :as json]
             [martian.core :as martian]
+            [martian.file :as file]
             [martian.interceptors :as interceptors]
             [martian.openapi :as openapi]
             [martian.yaml :as yaml]
@@ -80,13 +81,16 @@
 (defn bootstrap [api-root concise-handlers & [opts]]
   (martian/bootstrap api-root concise-handlers (merge default-opts opts)))
 
-(defn bootstrap-openapi [url & [{:keys [server-url] :as opts} get-swagger-opts]]
-  (let [body (:body (http/get url (normalize-request get-swagger-opts)))
-        definition (if (yaml/yaml-url? url)
-                     (yaml/yaml->edn body)
-                     (json/read-str body))
+(defn- load-definition [url load-opts]
+  (or (file/local-resource url)
+      (let [body (:body (http/get url (normalize-request load-opts)))]
+        (if (yaml/yaml-url? url)
+          (yaml/yaml->edn body)
+          (json/read-str body)))))
+
+(defn bootstrap-openapi [url & [{:keys [server-url] :as opts} load-opts]]
+  (let [definition (load-definition url load-opts)
         base-url (openapi/base-url url server-url definition)]
     (martian/bootstrap-openapi base-url definition (merge default-opts opts))))
 
 (def bootstrap-swagger bootstrap-openapi)
-
diff --git a/babashka-http-client/test/martian/babashka/http_client_test.clj b/babashka-http-client/test/martian/babashka/http_client_test.clj
index fe5eec0..8658952 100644
--- a/babashka-http-client/test/martian/babashka/http_client_test.clj
+++ b/babashka-http-client/test/martian/babashka/http_client_test.clj
@@ -160,6 +160,12 @@
     (is (contains? (set (map first (martian/explore m)))
                    :get-order-by-id))))
 
+(deftest local-file-test
+  (let [m (martian-http/bootstrap-openapi "public/openapi-test.json")]
+    (is (= "https://sandbox.example.com" (:api-root m)))
+    (is (= [[:list-items "Gets a list of items."]]
+           (martian/explore m)))))
+
 (if-bb
     nil
   (deftest babashka-test
diff --git a/clj-http-lite/src/martian/clj_http_lite.clj b/clj-http-lite/src/martian/clj_http_lite.clj
index 171de7c..24f6be5 100644
--- a/clj-http-lite/src/martian/clj_http_lite.clj
+++ b/clj-http-lite/src/martian/clj_http_lite.clj
@@ -1,6 +1,7 @@
 (ns martian.clj-http-lite
   (:require [clj-http.lite.client :as http]
             [cheshire.core :as json]
+            [martian.file :as file]
             [martian.yaml :as yaml]
             [martian.core :as martian]
             [martian.interceptors :as interceptors]
@@ -24,12 +25,16 @@
 (defn bootstrap [api-root concise-handlers & [opts]]
   (martian/bootstrap api-root concise-handlers (merge default-opts opts)))
 
-(defn bootstrap-openapi [url & [{:keys [server-url] :as opts} get-swagger-opts]]
-  (let [body (:body (http/get url (or get-swagger-opts {})))
-        ;; clj-http-lite does not support {:as :json} body conversion (yet) so we do it right here
-        definition (if (yaml/yaml-url? url)
-                     (yaml/yaml->edn body)
-                     (json/parse-string body keyword))
+(defn- load-definition [url load-opts]
+  (or (file/local-resource url)
+      (let [body (:body (http/get url (or load-opts {})))]
+        (if (yaml/yaml-url? url)
+          (yaml/yaml->edn body)
+          ;; clj-http-lite does not support {:as :json} body conversion (yet) so we do it right here
+          (json/parse-string body keyword)))))
+
+(defn bootstrap-openapi [url & [{:keys [server-url] :as opts} load-opts]]
+  (let [definition (load-definition url load-opts)
         base-url (openapi/base-url url server-url definition)]
     (martian/bootstrap-openapi base-url definition (merge default-opts opts))))
 
diff --git a/clj-http-lite/test/martian/clj_http_lite_test.clj b/clj-http-lite/test/martian/clj_http_lite_test.clj
index e648f74..7dbcabf 100644
--- a/clj-http-lite/test/martian/clj_http_lite_test.clj
+++ b/clj-http-lite/test/martian/clj_http_lite_test.clj
@@ -66,3 +66,9 @@
 
     (is (contains? (set (map first (martian/explore m)))
                    :get-order-by-id))))
+
+(deftest local-file-test
+  (let [m (martian-http/bootstrap-openapi "public/openapi-test.json")]
+    (is (= "https://sandbox.example.com" (:api-root m)))
+    (is (= [[:list-items "Gets a list of items."]]
+           (martian/explore m)))))
diff --git a/clj-http/src/martian/clj_http.clj b/clj-http/src/martian/clj_http.clj
index dd1422f..4912277 100644
--- a/clj-http/src/martian/clj_http.clj
+++ b/clj-http/src/martian/clj_http.clj
@@ -1,6 +1,7 @@
 (ns martian.clj-http
   (:require [clj-http.client :as http]
             [martian.core :as martian]
+            [martian.file :as file]
             [martian.interceptors :as interceptors]
             [martian.openapi :as openapi]
             [martian.yaml :as yaml]))
@@ -18,10 +19,14 @@
 (defn bootstrap [api-root concise-handlers & [opts]]
   (martian/bootstrap api-root concise-handlers (merge default-opts opts)))
 
-(defn bootstrap-openapi [url & [{:keys [server-url] :as opts} get-swagger-opts]]
-  (let [definition (if (yaml/yaml-url? url)
-                     (yaml/yaml->edn (:body (http/get url (dissoc get-swagger-opts :as))))
-                     (:body (http/get url (merge {:as :json} get-swagger-opts))))
+(defn- load-definition [url load-opts]
+  (or (file/local-resource url)
+      (if (yaml/yaml-url? url)
+        (yaml/yaml->edn (:body (http/get url (dissoc load-opts :as))))
+        (:body (http/get url (merge {:as :json} load-opts))))))
+
+(defn bootstrap-openapi [url & [{:keys [server-url] :as opts} load-opts]]
+  (let [definition (load-definition url load-opts)
         base-url (openapi/base-url url server-url definition)]
     (martian/bootstrap-openapi base-url definition (merge default-opts opts))))
 
diff --git a/clj-http/test/martian/clj_http_test.clj b/clj-http/test/martian/clj_http_test.clj
index 18632bf..deae4d8 100644
--- a/clj-http/test/martian/clj_http_test.clj
+++ b/clj-http/test/martian/clj_http_test.clj
@@ -67,3 +67,9 @@
 
     (is (contains? (set (map first (martian/explore m)))
                    :get-order-by-id))))
+
+(deftest local-file-test
+  (let [m (martian-http/bootstrap-openapi "public/openapi-test.json")]
+    (is (= "https://sandbox.example.com" (:api-root m)))
+    (is (= [[:list-items "Gets a list of items."]]
+           (martian/explore m)))))
diff --git a/cljs-http-promise/src/martian/cljs_http_promise.cljs b/cljs-http-promise/src/martian/cljs_http_promise.cljs
index 3d1af1f..9f3f350 100644
--- a/cljs-http-promise/src/martian/cljs_http_promise.cljs
+++ b/cljs-http-promise/src/martian/cljs_http_promise.cljs
@@ -28,8 +28,8 @@
 (defn bootstrap [api-root concise-handlers & [opts]]
   (martian/bootstrap api-root concise-handlers (merge default-opts opts)))
 
-(defn bootstrap-openapi [url & [{:keys [server-url trim-base-url?] :as opts}]]
-  (prom/then (http/get url {:as :json})
+(defn bootstrap-openapi [url & [{:keys [server-url trim-base-url?] :as opts} load-opts]]
+  (prom/then (http/get url (merge {:as :json} load-opts))
              (fn [response]
                (let [definition (:body response)
                      raw-base-url (openapi/base-url url server-url definition)
diff --git a/cljs-http-promise/test/martian/cljs_http_promise_test.cljs b/cljs-http-promise/test/martian/cljs_http_promise_test.cljs
index 31206e0..947f615 100644
--- a/cljs-http-promise/test/martian/cljs_http_promise_test.cljs
+++ b/cljs-http-promise/test/martian/cljs_http_promise_test.cljs
@@ -2,7 +2,8 @@
   (:require [martian.cljs-http-promise :as martian-http]
             [martian.core :as martian]
             [cljs.test :refer-macros [deftest is async]]
-            [promesa.core :as prom]))
+            [promesa.core :as prom])
+  (:require-macros [martian.file :refer [load-local-resource]]))
 
 (def swagger-url "http://localhost:8888/swagger.json")
 (def openapi-url "http://localhost:8888/openapi.json")
@@ -52,3 +53,9 @@
                               :get-order-by-id)))
              (prom/finally (fn []
                              (done))))))
+
+(deftest local-file-test
+  (let [m (martian/bootstrap-openapi "https://sandbox.example.com" (load-local-resource "public/openapi-test.json") martian-http/default-opts)]
+    (is (= "https://sandbox.example.com" (:api-root m)))
+    (is (= [[:list-items "Gets a list of items."]]
+           (martian/explore m)))))
diff --git a/cljs-http/src/martian/cljs_http.cljs b/cljs-http/src/martian/cljs_http.cljs
index cf91b7a..700390b 100644
--- a/cljs-http/src/martian/cljs_http.cljs
+++ b/cljs-http/src/martian/cljs_http.cljs
@@ -3,7 +3,7 @@
             [cljs.core.async :refer [<!]]
             [martian.core :as martian]
             [martian.interceptors :as i]
-            [martian.openapi :refer [openapi-schema?] :as openapi]
+            [martian.openapi :as openapi]
             [tripod.context :as tc]
             [clojure.string :as string])
   (:require-macros [cljs.core.async.macros :refer [go]]))
@@ -28,8 +28,8 @@
 (defn bootstrap [api-root concise-handlers & [opts]]
   (martian/bootstrap api-root concise-handlers (merge default-opts opts)))
 
-(defn bootstrap-openapi [url & [{:keys [server-url trim-base-url?] :as opts} get-swagger-opts]]
-  (go (let [definition (:body (<! (http/get url (merge {:as :json} get-swagger-opts))))
+(defn bootstrap-openapi [url & [{:keys [server-url trim-base-url?] :as opts} load-opts]]
+  (go (let [definition (:body (<! (http/get url (merge {:as :json} load-opts))))
             raw-base-url (openapi/base-url url server-url definition)
             base-url (if trim-base-url?
                        (string/replace raw-base-url #"/$" "")
diff --git a/cljs-http/test/martian/cljs_http_test.cljs b/cljs-http/test/martian/cljs_http_test.cljs
index 2a19faa..0bb81d4 100644
--- a/cljs-http/test/martian/cljs_http_test.cljs
+++ b/cljs-http/test/martian/cljs_http_test.cljs
@@ -1,9 +1,10 @@
 (ns martian.cljs-http-test
   (:require [martian.cljs-http :as martian-http]
             [martian.core :as martian]
-            [cljs.test :refer-macros [deftest testing is run-tests async]]
-            [cljs.core.async :refer [<! timeout]])
-  (:require-macros [cljs.core.async.macros :refer [go]]))
+            [cljs.test :refer-macros [deftest is async]]
+            [cljs.core.async :refer [<!]])
+  (:require-macros [cljs.core.async.macros :refer [go]]
+                   [martian.file :refer [load-local-resource]]))
 
 (def swagger-url "http://localhost:8888/swagger.json")
 (def openapi-url "http://localhost:8888/openapi.json")
@@ -50,3 +51,9 @@
                (is (contains? (set (map first (martian/explore m)))
                               :get-order-by-id)))
              (done))))
+
+(deftest local-file-test
+  (let [m (martian/bootstrap-openapi "https://sandbox.example.com" (load-local-resource "public/openapi-test.json") martian-http/default-opts)]
+    (is (= "https://sandbox.example.com" (:api-root m)))
+    (is (= [[:list-items "Gets a list of items."]]
+           (martian/explore m)))))
diff --git a/core/src/martian/file.clj b/core/src/martian/file.clj
new file mode 100644
index 0000000..54f97e4
--- /dev/null
+++ b/core/src/martian/file.clj
@@ -0,0 +1,19 @@
+(ns martian.file
+  (:require [clojure.java.io :as io]
+            [martian.yaml :as yaml]
+            [clojure.string :as str]
+            [cheshire.core :as json]))
+
+(defn local-resource [url]
+  (when-let [r (some-> (or (io/resource url)
+                           (let [f (io/file url)]
+                             (when (.exists f)
+                               f)))
+                       slurp)]
+    (cond
+      (yaml/yaml-url? url) (yaml/yaml->edn r)
+      (str/ends-with? url ".edn") (read-string r)
+      (str/ends-with? url ".json") (json/decode r keyword))))
+
+(defmacro load-local-resource [url]
+  (local-resource url))
diff --git a/hato/src/martian/hato.clj b/hato/src/martian/hato.clj
index 1a582be..9a18eed 100644
--- a/hato/src/martian/hato.clj
+++ b/hato/src/martian/hato.clj
@@ -1,6 +1,7 @@
 (ns martian.hato
   (:require [hato.client :as http]
             [martian.core :as martian]
+            [martian.file :as file]
             [martian.interceptors :as interceptors]
             [martian.openapi :as openapi]
             [martian.yaml :as yaml]
@@ -55,10 +56,14 @@
 (defn bootstrap [api-root concise-handlers & [opts]]
   (martian/bootstrap api-root concise-handlers (merge default-opts opts)))
 
-(defn bootstrap-openapi [url & [{:keys [server-url] :as opts} get-swagger-opts]]
-  (let [definition (if (yaml/yaml-url? url)
-                     (yaml/yaml->edn (:body (http/get url (dissoc get-swagger-opts :as))))
-                     (:body (http/get url (merge {:as :json} get-swagger-opts))))
+(defn- load-definition [url load-opts]
+  (or (file/local-resource url)
+      (if (yaml/yaml-url? url)
+        (yaml/yaml->edn (:body (http/get url (dissoc load-opts :as))))
+        (:body (http/get url (merge {:as :json} load-opts))))))
+
+(defn bootstrap-openapi [url & [{:keys [server-url] :as opts} load-opts]]
+  (let [definition (load-definition url load-opts)
         base-url (openapi/base-url url server-url definition)]
     (martian/bootstrap-openapi base-url definition (merge default-opts opts))))
 
diff --git a/hato/test/martian/hato_test.clj b/hato/test/martian/hato_test.clj
index 34bba10..c7068db 100644
--- a/hato/test/martian/hato_test.clj
+++ b/hato/test/martian/hato_test.clj
@@ -122,3 +122,9 @@
 
     (is (contains? (set (map first (martian/explore m)))
                    :get-order-by-id))))
+
+(deftest local-file-test
+  (let [m (martian-http/bootstrap-openapi "public/openapi-test.json")]
+    (is (= "https://sandbox.example.com" (:api-root m)))
+    (is (= [[:list-items "Gets a list of items."]]
+           (martian/explore m)))))
diff --git a/httpkit/src/martian/httpkit.clj b/httpkit/src/martian/httpkit.clj
index 33e6d29..af9766b 100644
--- a/httpkit/src/martian/httpkit.clj
+++ b/httpkit/src/martian/httpkit.clj
@@ -1,6 +1,7 @@
 (ns martian.httpkit
   (:require [org.httpkit.client :as http]
             [martian.core :as martian]
+            [martian.file :as file]
             [martian.interceptors :as interceptors]
             [martian.openapi :as openapi]
             [martian.yaml :as yaml]
@@ -29,13 +30,17 @@
 (defn bootstrap [api-root concise-handlers & [opts]]
   (martian/bootstrap api-root concise-handlers (merge default-opts opts)))
 
-(defn bootstrap-openapi [url & [{:keys [server-url] :as opts} get-swagger-opts]]
-  (let [definition @(http/get url
-                              (merge {:as :text} get-swagger-opts)
-                              (fn [{:keys [body]}]
-                                (if (yaml/yaml-url? url)
-                                  (yaml/yaml->edn body)
-                                  (json/decode body keyword))))
+(defn- load-definition [url load-opts]
+  (or (file/local-resource url)
+      @(http/get url
+                 (merge {:as :text} load-opts)
+                 (fn [{:keys [body]}]
+                   (if (yaml/yaml-url? url)
+                     (yaml/yaml->edn body)
+                     (json/decode body keyword))))))
+
+(defn bootstrap-openapi [url & [{:keys [server-url] :as opts} load-opts]]
+  (let [definition (load-definition url load-opts)
         base-url (openapi/base-url url server-url definition)]
     (martian/bootstrap-openapi base-url definition (merge default-opts opts))))
 
diff --git a/httpkit/test/martian/httpkit_test.clj b/httpkit/test/martian/httpkit_test.clj
index 58c5952..dce2f88 100644
--- a/httpkit/test/martian/httpkit_test.clj
+++ b/httpkit/test/martian/httpkit_test.clj
@@ -67,3 +67,9 @@
 
     (is (contains? (set (map first (martian/explore m)))
                    :get-order-by-id))))
+
+(deftest local-file-test
+  (let [m (martian-http/bootstrap-openapi "public/openapi-test.json")]
+    (is (= "https://sandbox.example.com" (:api-root m)))
+    (is (= [[:list-items "Gets a list of items."]]
+           (martian/explore m)))))