diff --git a/core/core/src/lib.rs b/core/core/src/lib.rs
index 5a83622b14ac..156f8e0dec5f 100644
--- a/core/core/src/lib.rs
+++ b/core/core/src/lib.rs
@@ -34,6 +34,16 @@ pub mod layers;
 pub mod raw;
 pub mod services;
 
+/// Re-export of the [`reqsign_core`] crate that services sign requests with.
+///
+/// Service builders that accept credentials from the application take `reqsign`
+/// types in their signatures, such as `ProvideCredentialChain` in
+/// `opendal_service_s3::S3::credential_provider_chain`. Implement providers
+/// against this re-export rather than depending on `reqsign-core` directly, so
+/// that the types always match the ones the services are built with.
+#[cfg(feature = "reqsign")]
+pub use reqsign_core;
+
 #[cfg(test)]
 mod tests {
     use super::*;
diff --git a/core/services/azblob/src/backend.rs b/core/services/azblob/src/backend.rs
index 62a41c877e85..5208c4350521 100644
--- a/core/services/azblob/src/backend.rs
+++ b/core/services/azblob/src/backend.rs
@@ -244,6 +244,10 @@ impl AzblobBuilder {
     }
 
     /// Replace the credential providers with a custom chain.
+    ///
+    /// Build the chain from [`opendal_core::reqsign_core`] and
+    /// [`crate::reqsign_azure_storage`] so that its types match the ones this
+    /// service is built with.
     pub fn credential_provider_chain(mut self, chain: ProvideCredentialChain<Credential>) -> Self {
         self.credential_providers = Some(chain);
         self
diff --git a/core/services/azblob/src/lib.rs b/core/services/azblob/src/lib.rs
index 98b5b7ebb9ec..b93fc2ad3557 100644
--- a/core/services/azblob/src/lib.rs
+++ b/core/services/azblob/src/lib.rs
@@ -46,3 +46,13 @@ pub mod writer;
 
 pub use backend::AzblobBuilder as Azblob;
 pub use config::AzblobConfig;
+
+/// Re-export of the [`reqsign_azure_storage`] crate that this service signs
+/// requests with.
+///
+/// [`Azblob::credential_provider_chain`] takes a chain of providers for
+/// [`reqsign_azure_storage::Credential`]. Implement providers against this
+/// re-export and [`opendal_core::reqsign_core`] rather than depending on the
+/// `reqsign` crates directly, so that the types always match the ones this
+/// service is built with.
+pub use reqsign_azure_storage;
diff --git a/core/services/azdls/src/backend.rs b/core/services/azdls/src/backend.rs
index 41625f8876ee..f7fb7d33b706 100644
--- a/core/services/azdls/src/backend.rs
+++ b/core/services/azdls/src/backend.rs
@@ -191,6 +191,10 @@ impl AzdlsBuilder {
     }
 
     /// Replace the credential providers with a custom chain.
+    ///
+    /// Build the chain from [`opendal_core::reqsign_core`] and
+    /// [`crate::reqsign_azure_storage`] so that its types match the ones this
+    /// service is built with.
     pub fn credential_provider_chain(mut self, chain: ProvideCredentialChain<Credential>) -> Self {
         self.credential_providers = Some(chain);
         self
diff --git a/core/services/azdls/src/lib.rs b/core/services/azdls/src/lib.rs
index 83ab1ba373f2..8f37ea44af17 100644
--- a/core/services/azdls/src/lib.rs
+++ b/core/services/azdls/src/lib.rs
@@ -43,3 +43,13 @@ mod writer;
 
 pub use backend::AzdlsBuilder as Azdls;
 pub use config::AzdlsConfig;
+
+/// Re-export of the [`reqsign_azure_storage`] crate that this service signs
+/// requests with.
+///
+/// [`Azdls::credential_provider_chain`] takes a chain of providers for
+/// [`reqsign_azure_storage::Credential`]. Implement providers against this
+/// re-export and [`opendal_core::reqsign_core`] rather than depending on the
+/// `reqsign` crates directly, so that the types always match the ones this
+/// service is built with.
+pub use reqsign_azure_storage;
diff --git a/core/services/gcs-grpc/src/backend.rs b/core/services/gcs-grpc/src/backend.rs
index 019940f563df..931e32c06ff2 100644
--- a/core/services/gcs-grpc/src/backend.rs
+++ b/core/services/gcs-grpc/src/backend.rs
@@ -105,6 +105,10 @@ impl GcsGrpcBuilder {
     }
 
     /// Set a custom Google credential provider.
+    ///
+    /// Implement the provider against [`opendal_core::reqsign_core`] and
+    /// [`crate::reqsign_google`] so that its types match the ones this service is
+    /// built with.
     pub fn credential_provider(
         mut self,
         provider: impl ProvideCredential<Credential = Credential> + 'static,
@@ -118,6 +122,10 @@ impl GcsGrpcBuilder {
     }
 
     /// Set a custom Google credential provider chain.
+    ///
+    /// Build the chain from [`opendal_core::reqsign_core`] and
+    /// [`crate::reqsign_google`] so that its types match the ones this service is
+    /// built with.
     pub fn credential_provider_chain(mut self, chain: ProvideCredentialChain<Credential>) -> Self {
         self.credential_provider_chain = Some(chain);
         self
diff --git a/core/services/gcs-grpc/src/lib.rs b/core/services/gcs-grpc/src/lib.rs
index 8a9a078b679e..fc6f555325c0 100644
--- a/core/services/gcs-grpc/src/lib.rs
+++ b/core/services/gcs-grpc/src/lib.rs
@@ -41,3 +41,13 @@ mod writer;
 
 pub use backend::GcsGrpcBuilder as GcsGrpc;
 pub use config::GcsGrpcConfig;
+
+/// Re-export of the [`reqsign_google`] crate that this service signs requests
+/// with.
+///
+/// [`GcsGrpc::credential_provider`] and [`GcsGrpc::credential_provider_chain`]
+/// take providers for [`reqsign_google::Credential`]. Implement providers against
+/// this re-export and [`opendal_core::reqsign_core`] rather than depending on the
+/// `reqsign` crates directly, so that the types always match the ones this
+/// service is built with.
+pub use reqsign_google;
diff --git a/core/services/gcs/src/backend.rs b/core/services/gcs/src/backend.rs
index 1a498a245910..61e575236b3c 100644
--- a/core/services/gcs/src/backend.rs
+++ b/core/services/gcs/src/backend.rs
@@ -156,6 +156,10 @@ impl GcsBuilder {
     /// Specify a customized credential provider used by this service.
     ///
     /// This provider will be pushed to the front of credential chain.
+    ///
+    /// Implement the provider against [`opendal_core::reqsign_core`] and
+    /// [`crate::reqsign_google`] so that its types match the ones this service is
+    /// built with.
     pub fn credential_provider(
         mut self,
         provider: impl ProvideCredential<Credential = Credential> + 'static,
@@ -168,6 +172,10 @@ impl GcsBuilder {
     /// Specify a customized credential provider chain used by this service.
     ///
     /// This chain will be pushed to the front of default chain.
+    ///
+    /// Build the chain from [`opendal_core::reqsign_core`] and
+    /// [`crate::reqsign_google`] so that its types match the ones this service is
+    /// built with.
     pub fn credential_provider_chain(mut self, chain: ProvideCredentialChain<Credential>) -> Self {
         self.credential_provider_chain = Some(chain);
         self
diff --git a/core/services/gcs/src/lib.rs b/core/services/gcs/src/lib.rs
index ba11abf10703..fc6d1f14c589 100644
--- a/core/services/gcs/src/lib.rs
+++ b/core/services/gcs/src/lib.rs
@@ -33,6 +33,16 @@ mod writer;
 pub use backend::GcsBuilder as Gcs;
 pub use config::GcsConfig;
 
+/// Re-export of the [`reqsign_google`] crate that this service signs requests
+/// with.
+///
+/// [`Gcs::credential_provider`] and [`Gcs::credential_provider_chain`] take
+/// providers for [`reqsign_google::Credential`]. Implement providers against this
+/// re-export and [`opendal_core::reqsign_core`] rather than depending on the
+/// `reqsign` crates directly, so that the types always match the ones this
+/// service is built with.
+pub use reqsign_google;
+
 /// URI scheme used for service registration and scheme-driven construction.
 pub const GCS_SCHEME: &str = "gcs";
 
diff --git a/core/services/s3/src/backend.rs b/core/services/s3/src/backend.rs
index 14e0354a3c50..6bc2498ea832 100644
--- a/core/services/s3/src/backend.rs
+++ b/core/services/s3/src/backend.rs
@@ -494,6 +494,10 @@ impl S3Builder {
     }
 
     /// Replace the credential providers with a custom chain.
+    ///
+    /// Build the chain from [`opendal_core::reqsign_core`] and
+    /// [`crate::reqsign_aws_v4`] so that its types match the ones this service is
+    /// built with.
     pub fn credential_provider_chain(mut self, chain: ProvideCredentialChain<Credential>) -> Self {
         self.credential_providers = Some(chain);
         self
diff --git a/core/services/s3/src/lib.rs b/core/services/s3/src/lib.rs
index 8e34b7dd12ff..31e4c949b8ae 100644
--- a/core/services/s3/src/lib.rs
+++ b/core/services/s3/src/lib.rs
@@ -32,6 +32,15 @@ mod writer;
 pub use backend::S3Builder as S3;
 pub use config::S3Config;
 
+/// Re-export of the [`reqsign_aws_v4`] crate that this service signs requests
+/// with.
+///
+/// [`S3::credential_provider_chain`] takes a chain of providers for
+/// [`reqsign_aws_v4::Credential`]. Implement providers against this re-export and
+/// [`opendal_core::reqsign_core`] rather than depending on the `reqsign` crates
+/// directly, so that the types always match the ones this service is built with.
+pub use reqsign_aws_v4;
+
 /// URI scheme used for service registration and scheme-driven construction.
 pub const S3_SCHEME: &str = "s3";