diff --git a/src/endpoints/workerskv/write_bulk.rs b/src/endpoints/workerskv/write_bulk.rs
index 5812a82e..23020bda 100644
--- a/src/endpoints/workerskv/write_bulk.rs
+++ b/src/endpoints/workerskv/write_bulk.rs
@@ -1,5 +1,6 @@
-use crate::framework::endpoint::{Endpoint, Method};
-
+use crate::framework::{response::ApiFailure, response::ApiErrors, response::ApiError, endpoint::{Endpoint, Method}};
+use reqwest;
+use std::collections::HashMap;
 /// Write Key-Value Pairs in Bulk
 /// Writes multiple key-value pairs to Workers KV at once.
 /// A 404 is returned if a write action is for a namespace ID the account doesn't have.
@@ -23,7 +24,37 @@ impl<'a> Endpoint<(), (), Vec<KeyValuePair>> for WriteBulk<'a> {
     fn body(&self) -> Option<Vec<KeyValuePair>> {
         Some(self.bulk_key_value_pairs.clone())
     }
-    // default content-type is already application/json
+    fn validate(&self)  -> Result<(), ApiFailure> {
+        if let Some(body) = self.body() {
+            // this matches the serialization in HttpApiClient
+            let json = serde_json::to_string(&body).map_err(|e|
+                ApiFailure::Error(
+                    reqwest::StatusCode::BAD_REQUEST,
+                    ApiErrors {
+                        errors: vec![ApiError {
+                            code: 400,
+                            message: format!("request body is malformed, failed json serialization: {}", e),
+                            other: HashMap::new(),
+                        }],
+                        other: HashMap::new(),
+                    }))?;
+
+            if json.len() >= 100_000_000 {
+                return Err(ApiFailure::Error(
+                    reqwest::StatusCode::PAYLOAD_TOO_LARGE,
+                    ApiErrors {
+                        errors: vec![ApiError {
+                            code: 413,
+                            message: "request payload too large, must be less than 100MB".to_owned(),
+                            other: HashMap::new(),
+                        }],
+                        other: HashMap::new(),
+                    },
+                ));
+            }
+        }
+        Ok(())
+    }
 }
 
 #[serde_with::skip_serializing_none]
@@ -35,3 +66,54 @@ pub struct KeyValuePair {
     pub expiration_ttl: Option<i64>,
     pub base64: Option<bool>,
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn write_bulk_validator_failure() {
+        let write_bulk_endpoint = WriteBulk{
+            account_identifier: "test_account_id",
+            namespace_identifier: "test_namespace",
+            bulk_key_value_pairs: vec![
+                KeyValuePair {
+                    key: "test".to_owned(),
+                    value: "X".repeat(100_000_000),
+                    expiration: None,
+                    expiration_ttl: None,
+                    base64: None
+                }
+            ]
+        };
+
+        match write_bulk_endpoint.validate() {
+            Ok(_) => assert!(false, "payload too large and validator passed incorrectly"),
+            Err(_) => assert!(true)
+        }
+    }
+
+    #[test]
+    fn write_bulk_validator_success() {
+        let write_bulk_endpoint = WriteBulk{
+            account_identifier: "test_account_id",
+            namespace_identifier: "test_namespace",
+            bulk_key_value_pairs: vec![
+                KeyValuePair {
+                    key: "test".to_owned(),
+                    // max is 99,999,972 chars for the val
+                    // the other 28 chars are taken by the key, property names, and json formatting chars
+                    value: "x".repeat(99_999_950),
+                    expiration: None,
+                    expiration_ttl: None,
+                    base64: None
+                }
+            ]
+        };
+
+        match write_bulk_endpoint.validate() {
+            Ok(_) => assert!(true),
+            Err(_) => assert!(false, "payload within bounds and validator failed incorrectly")
+        }
+    }
+}
diff --git a/src/framework/endpoint.rs b/src/framework/endpoint.rs
index 80712216..7404a836 100644
--- a/src/framework/endpoint.rs
+++ b/src/framework/endpoint.rs
@@ -1,5 +1,7 @@
 use crate::framework::response::ApiResult;
+use crate::framework::response::ApiFailure;
 use crate::framework::Environment;
+
 use serde::Serialize;
 use url::Url;
 
@@ -11,6 +13,7 @@ pub enum Method {
     Patch,
 }
 
+
 pub trait Endpoint<ResultType = (), QueryType = (), BodyType = ()>
 where
     ResultType: ApiResult,
@@ -25,6 +28,10 @@ where
     fn body(&self) -> Option<BodyType> {
         None
     }
+    /// Some endpoints dont need to validate. That's OK.
+    fn validate(&self) -> Result<(), ApiFailure> {
+        Ok(())
+    }
     fn url(&self, environment: &Environment) -> Url {
         Url::from(environment).join(&self.path()).unwrap()
     }
diff --git a/src/framework/mod.rs b/src/framework/mod.rs
index 528494dd..ccd58e37 100644
--- a/src/framework/mod.rs
+++ b/src/framework/mod.rs
@@ -80,6 +80,8 @@ impl<'a> ApiClient for HttpApiClient {
             }
         }
 
+        endpoint.validate()?;
+
         // Build the request
         let mut request = self
             .http_client
@@ -97,7 +99,6 @@ impl<'a> ApiClient for HttpApiClient {
         request = request.auth(&self.credentials);
 
         let response = request.send()?;
-
         map_api_response(response)
     }
 }