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The simplest way to build resilient applications.

As regular functions and services, in your existing infrastructure. On FaaS, K8s, servers, containers. Self-hosted or fully managed. Restate meets you where you are.

> Quickstart> Open Source Restate> See how it works> Restate Cloud
Workflows as code
Async Tasks, Timers, Schedulers
Event-driven Applications
MicroService Orchestration

Easy solutions for common challenges

Workflows as code

Workflows as code

Durable Execution ensures code runs reliably to the end, even in the presence of failures.

‍

  • Failures and errors are automatically retried (unless labeled as terminal errors)
  • Functions can memoize the results of code blocks, and actions like RPC, in a journal. Completed steps are not re-executed during retries, but replayed from the journal.
  • Workflows are built with regular code and control flow, no custom DSLs needed.
  • Durable sleeps let code wait and suspend for up to months

‍

> Learn More
JS
JS
Java
Kotlin
Python
Rust
Go

export default restate.service({
  name: "roleUpdate",
  handlers: {
    applyRoleUpdate: async (ctx, update) => {
      const { userId, role, permissions } = update;
      const applied = await ctx.run("apply new role", () =>
        applyUserRole(userId, role)
      );
      if (!applied) {
        return;
      }
      for (const permission of permissions) {
        await ctx.run("apply permission", () =>
          applyPermission(userId, permission)
        );
      }
    }
  }
});



@Service
public class RoleUpdateService {

    @Handler
    public void applyRoleUpdate(Context ctx, Update update) {

        boolean success = ctx.run("apply new role", BOOLEAN,
            () -> applyUserRole(update.getUserId(), update.getRole()));

        if (!success) {
            return;
        }

        for (String permission : update.getPermissions()) {
            ctx.run("apply permission",
                () -> applyPermission(update.getUserId(), permission));
        }
    }
}

API calls and webhooks

API calls and webhooks

Reliably join synchronous code and async events like webhooks

  • Webhooks/events are persisted in Restate’s log and reliably delivered to services
  • Persistent Promises/Futures easily join synchronous and asynchronous code paths
  • Durable execution ensures reliable completion, whether webhooks come after milliseconds or months, and avoid re-execution of completed steps.
> Learn More
JS
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Java
Kotlin
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const paymentSvc = restate.service({
  name: "payments",
  handlers: {
    processPayment: async (ctx, request) => {
      const webhookPromise = ctx.awakeable();
      const paymentIntent = await ctx.run("stripe call", () =>
        createPaymentIntent({
          request,
          metadata: { restate_callback_id: webhookPromise.id }
        })
      );
      if (paymentIntent.status === "processing") {
        // synchronous response inconclusive, await webhook response
        const paymentIntentFromWebhook = await webhookPromise.promise;
        return verifyPayment(paymentIntentFromWebhook);
      } else {
        return verifyPayment(paymentIntent);
      }
    },
    processWebhook: async (ctx) => {
      const paymentIntent = verifyAndParseEvent(ctx.request());
      const webhookPromiseId = paymentIntent.metadata.restate_callback_id;
      ctx.resolveAwakeable(webhookPromiseId, paymentIntent);
    }
  }
});



@Service
public class PaymentService {
  @Handler
  public void processPayment(Context ctx, PaymentRequest request) {
    var webhookFuture = ctx.awakeable(SERDE);
    var payment = ctx.run("Stripe call", SERDE, () -> submitPayment(
            request, Map.of("restate_callback_id", webhookFuture.id())
    ));
    if (payment.getStatus().equals("processing")) {
      // synchronous response inconclusive, await webhook response
      var updatedPayment = webhookFuture.await();
      verifyPayment(updatedPayment);
    } else {
      verifyPayment(payment);
    }
  }
  @Handler
  public void processWebhook(Context ctx) {
    var paymentEvent = verifyAndParseEvent(ctx.request());
    String callbackId = paymentEvent.getMetadata().get("restate_callback_id");
    ctx.awakeableHandle(callbackId).resolve(SERDE, paymentEvent);
  }
}

Asynchronous Tasks

Asynchronous Tasks

All functions invoked through Restate are executed durably and asynchronous.

  • Deploy async functions serverless or as containers or processes.
  • Call functions synchronously, async, or delayed. Re-attach and await from anywhere.
  • Build async patterns like fan-out, fan-in, task chains, and subtasks simply with function calls and Futures/Promises.
  • Use persistent timers to schedule tasks into the future.
  • Use fine-grained virtual queues (via virtual objects) to enforce strict task order and concurrency
> Learn More
JS
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Java
Kotlin
Python
Rust
Go

// ------ service (= worker) ------
const asyncTaskService = restate.service({
    name: "taskWorker",
    handlers: { processPayment }
});
// ------ client ------
const rs = clients.connect({ url: process.env.RESTATE_URL });
const taskWorker = rs.serviceSendClient({ name: "taskWorker" });
// submit the payment task 
app.post('/charge/:paymentId', async (req, res) => {
    const taskHandle = await taskWorker.processPayment(
        { request: req.params },
        SendOpts.from({ idempotencyKey: req.params.paymentId })
    );
    res.json(taskHandle);
});
// await the payment task
app.get('/status', async (req,res) => {
        const taskHandle = req.body.json();
        const paymentResult = await restate.result(taskHandle); 
        res.join(paymentResult);
});



// --- start payment task ---
server.createContext("/charge", httpExchange -> {
  PaymentRequest req = parsePaymentRequest(httpExchange);
  SendResponse handle = AsyncTaskServiceClient
      .fromIngress(RESTATE_URI)
      .send()
      .processPayment(req, idempotencyKey(req.getPaymentId()));

  respondJson(httpExchange, handle);
});
//  --- connect to payment result ---
server.createContext("/status", httpExchange -> {
  String handle = parseToHandle(httpExchange);
  String response = IngressClient.defaultClient(RESTATE_URI)
      .invocationHandle(handle, STRING)
      .attach();
  respond(httpExchange, response);
});

Stateful Event Processing

Stateful Event Processing

Process events (for example from Kafka) with durable functions as event handlers and get fine-grained retries and workflow-as-code semantics.

  • No queue subscriptions, no manual offset management, scaling, or balancing
  • Deploy the event processing logic as serverless functions on FaaS
  • Keep exactly-once state, delay events, run multiple asynchronous steps or API calls.
  • Restate’s queue-per-key semantics mean no more head-of-the-line waiting effects
> Learn More
JS
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Java
Kotlin
Python
Rust
Go

const eventEnricher = restate.object({
  name: "eventEnricher",
  handlers: {
    userEvent: async (ctx, event) => {
      // remember event, time box 100 ms to collect features
      // before emitting result
      ctx.set("user", event);
      ctx.serviceSendClient(eventEnricher, { delay: 100 }).emit();
    },
    featureEvent: async (ctx, featureEvent) => {
      // merge feature into event
      const userEvent = (await ctx.get("user")) ?? {};
      (userEvent.features ??= []).push(featureEvent);
      ctx.set("user", userEvent)
    },
    emit: async (ctx) => {
      emit(ctx.key, await ctx.get("user"));
      ctx.clearAll();
    }
  }
})



@VirtualObject
public class EventEnricher {
    static final StateKey USER = StateKey.of("user", of(User.class));
    @Handler
    public void userEvent(ObjectContext ctx, User event) {
        ctx.set(USER, event);
        // time box 100 ms to collect features before emitting result
        EventEnricherClient.fromContext(ctx, ctx.key())
            .send(ofMillis(100)).emit();
    }
    @Handler
    public void featureEvent(ObjectContext ctx, Feature event) {
        User user = ctx.get(USER).orElse(new User());
        user.addFeature(event);
        ctx.set(USER, user);
    }
    @Handler
    public void emit(ObjectContext ctx) {
        send(ctx.key(), ctx.get(USER));
        ctx.clearAll();
    }
}

Durable Signals

Durable Signals

Create workflows and event handlers that reliably handle external signals, events, human input.

‍

  • Use durable Promises/Futures to intuitively model signals and conditions
  • Create signals from RPCs, webhooks, or Kafka events
  • Signals and events are persisted by Restate, no need for a queue
> Learn More
JS
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Java
Kotlin
Python
Rust
Go

export default workflow({
  name: "verify",
  handlers: {
    run: async (ctx, { email }) => {
      const secret = ctx.run("generate secret", () =>
        crypto.randomUUID()
      );
      await ctx.run("send email", () => sendEmail({ email, secret }));

      const clickSecret = await ctx.promise("email.clicked");
      return clickSecret == secret;
    },
    click: (ctx, { secret }) => {
      ctx.promise("email.clicked").resolve(secret);
    },
  },
});






@Workflow
public class SecretVerifier {

    static final DurablePromiseKey EMAIL_CLICKED =
            DurablePromiseKey.of("email_clicked", JsonSerdes.STRING);

    @Workflow
    public boolean run(WorkflowContext ctx, Email email) {
        String secret = ctx.random().nextUUID().toString();
        ctx.run("send email",
            () -> sendEmailWithLink(email, secret));

        String clickSecret = ctx.promise(EMAIL_CLICKED).awaitable().await();
        return clickSecret.equals(secret);
    }

    @Handler
    public void click(SharedWorkflowContext ctx, String secret) {
        ctx.promiseHandle(EMAIL_CLICKED).resolve(secret);
    }
}

Idempotency

Idempotency

Add idempotency to any RPC- or event handler.

‍

  • Every RPC- and event handler call accepts an idempotency key
  • Use idempotency keys to re-attach to an ongoing invocation
  • Calls from within a durable execution context are automatically idempotent
> Learn More
JS
JS
Java
Kotlin
Python
Rust
Go

const rs = restate.connect({ url: process.env.RESTATE_URL });
app.get('/reserve/:product/:reservationId', async (req, res) => {
  const { product, reservationId } = req.params;
  const products = rs.serviceClient(ProductService);
  const reservation = await products.reserve(
    product,
    Opts.from({ idempotencyKey : reservationId })
  );
  res.json(reservation);
})



server.createContext("/reserve", httpExchange -> {
      ReservationRequest req = parseRequest(httpExchange.getRequestBody());
      // derive an idempotency key from the parameters
      var idempotencyOps = CallRequestOptions.DEFAULT
          .withIdempotency(req.getReservationId());
      // add idempotency opts to the request to let the service automatically
      // fuse repeated requests
      Reservation reservation = ProductServiceClient
          .fromIngress(RESTATE_RUNTIME_ENDPOINT)
          .reserve(req.getProduct(), idempotencyOps);
      sendResponse(httpExchange, reservation);
    });

Sagas

Sagas

Implements robust sagas and compensation patterns: long-running transactions that undo previous actions when they need to abort and roll back.

‍

  • Reliably pick up after failures to trigger compensations
  • Ensure compensations happen even upon failures during the compensation phase
  • Use standard Exception/Error mechanisms and control flow rather than complex DSLs.
> Learn More
JS
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Java
Kotlin
Python
Rust
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async function reservation(ctx, products) {
  const reservations = [];
  try {
    for (const product of products) {
      const reservation = await ctx.run(`reserve ${product}`,
          () => reserve(product));
      reservations.push(reservation);
    }
  } catch (error) {
    if (error instanceof TerminalError) {
      for (const reservation of reservations) {
        await ctx.run("undo reserve", () => 
            cancelReservation(reservation));
      }
    }
    throw error;
  }
}



@Handler
public void reserveAllProducts(Context ctx, Product[] products) {
    final List reservations = new ArrayList<>();
    try {
        for (Product product : products) {
            Reservation res = ctx.run("Reserve " + product.getId(),
                RESERVE_SERDE, () -> reserve(product)
            );
            reservations.add(res);
        }
    } catch (TerminalException e) {
        reservations.forEach(res -> {
            ctx.run("Undo reservation", () -> cancelReservation(res));
        });
        throw e;
    }
}

State machines

State machines

Create consistent and scalable State Machines without databases or transactions
‍

  • Run millions of State Machines that maintain state directly in the context of their handlers
  • State changes commit atomically with function execution, for rock-solid consistency
  • Single-writer semantics for a dead simple concurrency model. A virtual queue per state machine for efficiency and scalability.
  • State transition can be workflows with all the features from durable execution
> Learn More
JS
JS
Java
Kotlin
Python
Rust
Go

const paymentSvc = restate.object({
  name: "payments",
  handlers: {
    makePayment: async (ctx, payment) => {
      const paymentId = ctx.key;
      switch (await ctx.get("status")) {
        case "CANCELLED":
            return `${paymentId} was cancelled before`;
        case "SUCCESS":
            return `${paymentId} previously completed`;
      }
      wireFunds(payment);
      ctx.set("status", "SUCCESS");
      ctx.set("payment", payment);
    },
    cancelPayment: async (ctx) => {
      const status = await ctx.get("status");
      if (status === "SUCCESS") {
        const payment = await ctx.get("payment");
        refund(payment);
      }
      ctx.set("status", "CANCELLED");
    }
  }
});



@VirtualObject
public class PaymentStateMachine {
  @Handler
  public String makePayment(ObjectContext ctx, PaymentRequest payment) {
    String paymentId = ctx.key();
    switch (ctx.get(STATE_STATUS).orElse(NEW)) {
      case CANCELLED: return paymentId + " was cancelled before";
      case SUCCESS:   return paymentId + " was previously completed";
    }
    wireFunds(payment);
    ctx.set(STATE_STATUS, SUCCESS);
    ctx.set(STATE_PAYMENT_REQUEST, payment);
    return paymentId + " was successfully processed";
  }
  @Handler
  public void cancelPayment(ObjectContext ctx) {
    Status status = ctx.get(STATE_STATUS).orElse(NEW);
    if (status == SUCCESS) {
      PaymentRequest payment = ctx.get(STATE_PAYMENT_REQUEST).get();
      refund(payment);
    }
    ctx.set(STATE_STATUS, CANCELLED);
  }
}

A simple and powerful programming model

Restate provides distributed durable version of your everyday building blocks.

> See how it works

Durable Execution

Functions/Services that handle retries, recovery, asynchrony, idempotency.

Virtual Objects

Persistent state directly in your objects with a simple concurrency model.

Durable Promises

Transparent and fault-tolerant communication across services, processes, and time.

Single binary, no dependencies, built in Rust.

A system that runs locally and on-prem just as well as in the 
cloud. Restate server comes as a single binary. Simple to run, 
simple to operate.

Fully self-contained, resource-efficient, resilient, thanks to 
Rust’s magic.

Stellar local dev-experience

What’s better than a local dev server?

Running the real system on your laptop or in your CI pipeline. No subtle quirks and differences between dev- and prod setups.

Your Restate-powered code is just functions/services. Develop them with the tools you know and love.

Low latency
workflows-as-code

Restate’s event-driven architecture offers very low latencies for durable invocations and workflow-as-code steps, supporting workflows on latency-critical and synchronous code paths.

> See how it works

Built by the original creators of Apache Flink

Restate is built by the original creators of Apache Flink and lead engineers from Meta's data infrastructure.
‍
We built and operated some of the largest event processing setups on the planet.

Works with

TypeScript / JavaScript

Java

Kotlin

Python

Go

Rust

Restate Cloud: The zero-infrastructure option

Get a fully serverless Restate experience, managed by the developers of the system.

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Baked-in powerful tools to operate applications

Built-in OTel tracing, a powerful CLI, and a
SQL engine help you understand what is happening in your distributed application.

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