Free · No Install · Browser-Based

Test gRPC API Online
Instantly — No Setup Required

Send gRPC-Web calls directly from your browser. Test unary and server-streaming endpoints with custom headers, metadata, JSON payloads, and get real-time response inspection.

Send gRPC Request Now
Unary
Unary Calls
Stream
Server-Streaming
Meta
Custom Metadata
Free
No Login Needed

gRPC API Tester

Configure your gRPC-Web request below. All requests are sent directly from your browser to the target server — no data is stored on our end.

Custom HTTP Headers (Authorization, Accept, etc.)
gRPC Metadata (sent as grpc-metadata-* headers)
gRPC Response
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gRPC Status
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Latency (ms)
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Response Size
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Messages
Response Body

                


                
                

                    
 Response Headers

                    

                        
HeaderValue

                        
                    

                


                
                

                    
 gRPC Trailers

                    

                        
Trailer KeyValue

                        
                    

                


                
                
            


            
            

                

                    
                    
                    Request History
                    
                

                

                    

                        
No requests yet. Send your first gRPC call above.

                    

                    
                

            


            
            

                 Disclaimer: This tool sends requests from your browser directly to the specified gRPC-Web endpoint. SEOWebChecker.com does not store, log, or process your request payloads or API responses. gRPC® is a registered trademark of Google LLC. Protocol Buffers® is a trademark of Google LLC. All third-party trademarks are the property of their respective owners. This is an independent testing tool with no affiliation to Google or any gRPC service provider.
            

        

    







    

        

            
Why Use Our Tool

            
Advanced gRPC API Tester Features

            
The most comprehensive free browser-based gRPC testing tool — packed with developer-grade features for debugging, validation, and real-time inspection.

        

        

            

                

                
Unary & Server-Streaming

                
Test both gRPC unary calls (single request/response) and server-streaming RPCs that return multiple messages over time — all from the same interface.

            

            

                

                
Custom Metadata & Headers

                
Add arbitrary HTTP headers (Authorization, Accept, X-Custom-Header) and gRPC metadata key-value pairs to simulate real-world authenticated requests.

            

            

                

                
JSON Body Editor & Formatter

                
Write your request payload in JSON, auto-format it with one click, and get instant validation feedback before sending — no manual JSON debugging needed.

            

            

                

                
Response Timing & Stats

                
See exact response latency in milliseconds, response size in bytes, number of stream messages, and the gRPC status code — all displayed clearly after each call.

            

            

                

                
Trailer & Header Inspection

                
Inspect both response headers and gRPC trailers (grpc-status, grpc-message, grpc-encoding) returned by the server — essential for debugging gRPC error responses.

            

            

                

                
Request History Log

                
Every request is logged in-session with its method path, status code, latency, and timestamp. Click any history item to reload the request configuration instantly.

            

            

                

                
Real-time Input Validation

                
URL format, method path syntax, JSON body structure, and metadata keys are validated as you type — with clear inline error messages to fix issues before sending.

            

            

                

                
Copy, Download & Export

                
Copy the full response to clipboard or download it as a structured .txt report — including request config, status, headers, trailers, body, and latency details.

            

            

                

                
Timeout & Deadline Control

                
Set browser-level fetch timeouts (5s–60s) and the gRPC-Timeout header independently — test how your service behaves when deadlines are exceeded.

            

        

    







    

        

            
Simple Process

            
How to Test a gRPC API Online

            
Send your first gRPC-Web request in under a minute — no CLI tools, no protoc, no dependencies.

        

        

            

                
1

                
Enter Server URL

                
Provide your gRPC-Web server base URL (e.g. https://api.example.com). The server must support gRPC-Web protocol and respond with appropriate CORS headers.

            

            

                
2

                
Specify Method Path

                
Enter the fully-qualified method path matching your proto definition — e.g. /helloworld.Greeter/SayHello. This tells the server which RPC to invoke.

            

            

                
3

                
Configure Headers & Body

                
Set your call type (Unary or Streaming), add HTTP headers for authentication, add gRPC metadata, and write your JSON request body. Use "Format JSON" to auto-prettify.

            

            

                
4

                
Send & Inspect Response

                
Click Send gRPC Request. The tool displays status code, latency, response body (formatted JSON), response headers, gRPC trailers, and stream messages in real-time.

            

        

    







    

        

            
What Is gRPC? How to Test gRPC APIs & Best Practices

            
gRPC (Google Remote Procedure Call) is an open-source, high-performance RPC framework originally developed by Google. It uses HTTP/2 as its transport layer, Protocol Buffers (protobuf) for efficient binary serialization, and supports four communication patterns: unary, server-streaming, client-streaming, and bidirectional streaming. Because of its speed, strict typing, and cross-language support, gRPC has become the protocol of choice for microservices, cloud-native APIs, and real-time data pipelines.

            
Why test gRPC APIs? Unlike REST, gRPC services are defined by .proto schema files and communicate over binary-encoded messages. This makes gRPC APIs harder to test with conventional browser-based tools. Dedicated gRPC testing ensures your service correctly implements its proto contract, handles edge-case inputs gracefully, returns proper gRPC status codes (OK, NOT_FOUND, INVALID_ARGUMENT, UNAUTHENTICATED), and propagates metadata and trailers correctly to clients.

            
How gRPC-Web enables browser testing: Native gRPC relies on HTTP/2 trailers which browsers do not expose to JavaScript. gRPC-Web is a browser-compatible variant that wraps gRPC messages in a format accessible via the Fetch API, enabling browser-based clients and online tools like this one to communicate with gRPC-Web-compatible servers (configured with an Envoy proxy or a native gRPC-Web server implementation).

            
Best practices for gRPC API testing: Always validate your JSON payload matches the expected proto message structure. Test all four gRPC status code categories — success (OK), client errors (INVALID_ARGUMENT, NOT_FOUND, PERMISSION_DENIED), and server errors (INTERNAL, UNAVAILABLE). Verify grpc-status and grpc-message trailers in every response. Test with and without authorization metadata. For streaming RPCs, verify the server correctly terminates the stream and sends the final trailer. Set realistic deadlines and test timeout behavior. Use request IDs (x-request-id) to trace calls across distributed systems.

        

    







    

        

            
FAQ

            
Frequently Asked Questions — gRPC API Testing

            
Everything developers need to know about testing gRPC APIs online.

        

        

            

                
                
gRPC is a high-performance open-source RPC framework developed by Google. It uses HTTP/2 for multiplexed transport and Protocol Buffers for compact binary serialization. It supports unary, server-streaming, client-streaming, and bidirectional-streaming call patterns. gRPC is widely used in microservices for its speed, strong typing, and first-class support for multiple programming languages.

            

            

                
                
Enter your gRPC-Web server URL, specify the method path (e.g. /helloworld.Greeter/SayHello), choose the call type (Unary or Server-Streaming), add any required headers or metadata, write your JSON request body, and click Send gRPC Request. The response — including status, trailers, and body — is displayed instantly with latency metrics.

            

            

                
                
gRPC-Web is a browser-compatible subset of gRPC. Standard gRPC relies on HTTP/2 trailing headers (trailers) that browsers do not expose via JavaScript. gRPC-Web works around this by encapsulating trailers in the response body, allowing browser clients to read them via the Fetch API. Your gRPC server must support gRPC-Web natively or sit behind a gRPC-Web proxy (e.g. Envoy) for this tool to work.

            

            

                
                
The gRPC method path follows the format /package.ServiceName/MethodName, derived directly from your .proto file. For example, if your proto defines package helloworld, service Greeter, and rpc SayHello, the path is /helloworld.Greeter/SayHello. This path is appended to the server base URL to form the full gRPC-Web request URL.

            

            

                
                
gRPC metadata is arbitrary key-value data sent alongside a request or response, separate from the message payload — similar to HTTP headers. Common metadata includes authorization tokens, client version info, request trace IDs, and custom routing hints. In gRPC-Web, metadata is transmitted as HTTP headers prefixed with grpc-metadata- (or sent directly as standard HTTP headers like authorization).

            

            

                
                
Browsers enforce CORS (Cross-Origin Resource Sharing). For this browser-based tool to reach your gRPC-Web server, the server must respond with Access-Control-Allow-Origin (and Access-Control-Allow-Headers, Access-Control-Allow-Methods) headers. If testing a local development server, configure CORS in your gRPC-Web proxy (Envoy) or server. A CORS error means the server refused the browser's preflight OPTIONS request.

            

            

                
                
Key gRPC status codes to test: OK (0 – success), CANCELLED (1), INVALID_ARGUMENT (3 – bad input), NOT_FOUND (5), ALREADY_EXISTS (6), PERMISSION_DENIED (7), UNAUTHENTICATED (16), RESOURCE_EXHAUSTED (8 – rate limiting), INTERNAL (13 – server error), UNAVAILABLE (14 – service down), DEADLINE_EXCEEDED (4 – timeout). The grpc-status trailer in the response contains the numeric code.

            

            

                
                
Yes, completely free. No registration, login, or subscription is required. All gRPC requests are made directly from your browser to your server — we do not store, log, or proxy your request payloads or responses. You can use this tool as many times as needed at no cost.

            

        

    







    

        

            
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