diff --git a/pkg/connector/apikey.go b/pkg/connector/apikey.go
index fb4db5913..3e4784259 100644
--- a/pkg/connector/apikey.go
+++ b/pkg/connector/apikey.go
@@ -24,6 +24,16 @@ import (
 
 type APIKeyConnection struct {
 	APIKey string `json:"api_key"`
+	// Header selects how the API key is presented on outbound requests.
+	// Empty (the default) sends it as `Authorization: Bearer <key>`,
+	// which every OAuth-style and standard API-key connector uses. A
+	// non-empty value (e.g. "x-api-key") sends the raw key in that
+	// request header instead and omits Authorization entirely —
+	// required by providers such as Anthropic that reject Bearer auth
+	// and return 400 when both x-api-key and Authorization are present.
+	// It is populated from the provider Registration at connector
+	// creation time.
+	Header string `json:"header,omitempty"`
 }
 
 var _ Connection = (*APIKeyConnection)(nil)
@@ -37,13 +47,43 @@ func (c *APIKeyConnection) Scopes() []string {
 }
 
 func (c *APIKeyConnection) Client(ctx context.Context) (*http.Client, error) {
-	transport := &oauth2Transport{
-		token:      c.APIKey,
-		tokenType:  "Bearer",
-		underlying: httpclient.DefaultPooledTransport(httpclient.WithSSRFProtection()),
+	underlying := httpclient.DefaultPooledTransport(httpclient.WithSSRFProtection())
+
+	if c.Header != "" {
+		return &http.Client{
+			Transport: &apiKeyHeaderTransport{
+				header:     c.Header,
+				value:      c.APIKey,
+				underlying: underlying,
+			},
+		}, nil
 	}
 
-	return &http.Client{Transport: transport}, nil
+	return &http.Client{
+		Transport: &oauth2Transport{
+			token:      c.APIKey,
+			tokenType:  "Bearer",
+			underlying: underlying,
+		},
+	}, nil
+}
+
+// apiKeyHeaderTransport injects the API key into a custom request header
+// (for example "x-api-key") and, unlike oauth2Transport, never sets
+// Authorization. Providers such as Anthropic require the key in their
+// own header and reject requests that carry both that header and
+// Authorization.
+type apiKeyHeaderTransport struct {
+	header     string
+	value      string
+	underlying http.RoundTripper
+}
+
+func (t *apiKeyHeaderTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	req2 := req.Clone(req.Context())
+	req2.Header.Set(t.header, t.value)
+
+	return t.underlying.RoundTrip(req2)
 }
 
 func (c APIKeyConnection) MarshalJSON() ([]byte, error) {
diff --git a/pkg/connector/provider/registry.go b/pkg/connector/provider/registry.go
index 2492977df..3a1a75ed8 100644
--- a/pkg/connector/provider/registry.go
+++ b/pkg/connector/provider/registry.go
@@ -119,6 +119,19 @@ func (r *Registry) ProviderDisplayName(p coredata.ConnectorProvider) string {
 	return string(p)
 }
 
+// APIKeyHeader returns the request header an API-key connection for the
+// given provider must use to present its key. Empty means the default
+// `Authorization: Bearer` scheme; a value such as "x-api-key" means the
+// raw key is sent in that header instead. Returns empty for unknown
+// providers and for providers that do not customise the scheme.
+func (r *Registry) APIKeyHeader(p coredata.ConnectorProvider) string {
+	if reg, ok := r.Get(p); ok {
+		return reg.APIKeyHeader
+	}
+
+	return ""
+}
+
 // ProviderOAuth2Scopes returns the OAuth2 scopes the access review
 // driver for the given provider needs to list user accounts. Returns
 // nil for providers that do not need any scopes (Notion, Intercom)
diff --git a/pkg/connector/provider/types.go b/pkg/connector/provider/types.go
index 3f9e66ac8..0c02b5d21 100644
--- a/pkg/connector/provider/types.go
+++ b/pkg/connector/provider/types.go
@@ -56,6 +56,13 @@ type Registration struct {
 	SupportsAPIKey            bool
 	SupportsClientCredentials bool
 	ExtraSettings             []ExtraSetting
+	// APIKeyHeader selects how an API-key connection presents its key
+	// on outbound requests. Empty (the default) uses the standard
+	// `Authorization: Bearer <key>` scheme; a value such as "x-api-key"
+	// sends the raw key in that header instead and omits Authorization
+	// (Anthropic). It is consumed when the create-connector resolver
+	// builds the APIKeyConnection.
+	APIKeyHeader string
 
 	// Factory closures — wired by Stages 2 and 3.
 	NewDriver               func(context.Context, *http.Client, *coredata.Connector, *log.Logger) (drivers.Driver, error)
diff --git a/pkg/server/api/console/v1/connector_resolvers.go b/pkg/server/api/console/v1/connector_resolvers.go
index 2b51a4241..7a164fcc0 100644
--- a/pkg/server/api/console/v1/connector_resolvers.go
+++ b/pkg/server/api/console/v1/connector_resolvers.go
@@ -40,7 +40,10 @@ func (r *mutationResolver) CreateAPIKeyConnector(ctx context.Context, input type
 		OrganizationID: input.OrganizationID,
 		Provider:       input.Provider,
 		Protocol:       coredata.ConnectorProtocolAPIKey,
-		Connection:     &connector.APIKeyConnection{APIKey: input.APIKey},
+		Connection: &connector.APIKeyConnection{
+			APIKey: input.APIKey,
+			Header: r.providerRegistry.APIKeyHeader(input.Provider),
+		},
 	}
 
 	raw, err := apiKeyConnectorSettings(input)