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Low-Level KV Storage

Use the built-in key-value store on ActorContext for durable string and binary data alongside actor state.

Every Rivet Actor includes a lightweight key-value store on c.kv. It is useful for dynamic keys, blobs, or data that does not fit well in structured state.

If your data has a known schema, prefer state. KV is best for flexible or user-defined keys.

Basic Usage

Keys and values default to text, so you can use strings without extra options.

import { actor } from "rivetkit";

const greetings = actor({
  state: {},
  actions: {
    setGreeting: async (c, userId: string, message: string) => {
      await c.kv.put(`greeting:${userId}`, message);
    },
    getGreeting: async (c, userId: string) => {
      return await c.kv.get(`greeting:${userId}`);
    }
  }
});

Value Types

You can store binary values by passing Uint8Array or ArrayBuffer directly. Use type when reading to get the right return type.

import { actor } from "rivetkit";

const assets = actor({
  state: {},
  actions: {
    putAvatar: async (c, bytes: Uint8Array) => {
      await c.kv.put("avatar", bytes);
    },
    getAvatar: async (c) => {
      return await c.kv.get("avatar", { type: "binary" });
    },
    putSnapshot: async (c, data: ArrayBuffer) => {
      await c.kv.put("snapshot", data);
    }
  }
});

TypeScript returns a concrete type based on the option you pass in:

import { actor } from "rivetkit";

const example = actor({
  state: {},
  actions: {
    demo: async (c) => {
      const textValue = await c.kv.get("greeting");
      //    ^? string | null

      const bytes = await c.kv.get("avatar", { type: "binary" });
      //    ^? Uint8Array | null
    }
  }
});

Key Types

Keys accept either string or Uint8Array. String keys are encoded as UTF-8 by default.

When listing by prefix, you can control how keys are decoded with keyType. Returned keys have the prefix removed.

import { actor } from "rivetkit";

const example = actor({
  state: {},
  actions: {
    listGreetings: async (c) => {
      const results = await c.kv.list("greeting:", { keyType: "text" });

      for (const [key, value] of results) {
        console.log(key, value);
      }
    }
  }
});

If you use binary keys, set keyType: "binary" so the returned keys stay as Uint8Array.

Batch Operations

KV supports batch operations for efficiency. Defaults are still text for both keys and values.

import { actor } from "rivetkit";

const example = actor({
  state: {},
  actions: {
    batchOps: async (c) => {
      await c.kv.putBatch([
        ["alpha", "1"],
        ["beta", "2"],
      ]);

      const values = await c.kv.getBatch(["alpha", "beta"]);
    }
  }
});

API Reference

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