diff --git a/assembly/__tests__/runtime/runtime.spec.ts b/assembly/__tests__/runtime/runtime.spec.ts
index e6fb0f24..dcb2b093 100644
--- a/assembly/__tests__/runtime/runtime.spec.ts
+++ b/assembly/__tests__/runtime/runtime.spec.ts
@@ -65,6 +65,80 @@ describe("Encodings", () => {
   });
 });
 
+describe("Account env util", () => {
+  it("isValidAccountID", () => {
+    var accounts = [
+      "aa",
+      "a-a",
+      "a-aa",
+      "100",
+      "0o",
+      "com",
+      "near",
+      "bowen",
+      "b-o_w_e-n",
+      "b.owen",
+      "bro.wen",
+      "a.ha",
+      "a.b-a.ra",
+      "system",
+      "over.9000",
+      "google.com",
+      "illia.cheapaccounts.near",
+      "0o0ooo00oo00o",
+      "alex-skidanov",
+      "10-4.8-2",
+      "b-o_w_e-n",
+      "no_lols",
+      "0123456789012345678901234567890123456789012345678901234567890123",
+      // Valid, but can't be created
+      "near.a",
+      "a.a",
+    ];
+    for (var i = 0; i < accounts.length; i++) {
+      expect(env.isValidAccountID(accounts[i])).toBe(
+        true,
+        "valid accountId not recognized " + accounts[i]
+      );
+    }
+
+    accounts = [
+      "",
+      "a",
+      "A",
+      "Abc",
+      "-near",
+      "near-",
+      "-near-",
+      "near.",
+      ".near",
+      "near@",
+      "@near",
+      "неар",
+      "@@@@@",
+      "0__0",
+      "0_-_0",
+      "0_-_0",
+      "..",
+      "a..near",
+      "nEar",
+      "_bowen",
+      "hello world",
+      "abcdefghijklmnopqrstuvwxyz.abcdefghijklmnopqrstuvwxyz.abcdefghijklmnopqrstuvwxyz",
+      "01234567890123456789012345678901234567890123456789012345678901234",
+      // `@` separators are banned now
+      "some-complex-address@gmail.com",
+      "sub.buy_d1gitz@atata@b0-rg.c_0_m",
+    ];
+    for (i = 0; i < accounts.length; i++) {
+      expect(env.isValidAccountID(accounts[i])).toBe(
+        false,
+        "invalid accountId not detected " + accounts[i]
+      );
+    }
+  });
+});
+
 let outcome: Outcome;
 describe("outcome", () => {
   afterAll(() => {
diff --git a/assembly/sdk/env/env.ts b/assembly/sdk/env/env.ts
index 7857011f..25d74cae 100644
--- a/assembly/sdk/env/env.ts
+++ b/assembly/sdk/env/env.ts
@@ -62,6 +62,41 @@ export namespace env {
     return _storage_usage();
   }
 
+  // ############
+  // # Accounts #
+  // ############
+  export function isValidAccountID(accountId: string): boolean {
+    const MIN_ACCOUNT_ID_LEN = 2;
+    const MAX_ACCOUNT_ID_LEN = 64;
+    if (
+      accountId.length < MIN_ACCOUNT_ID_LEN ||
+      accountId.length > MAX_ACCOUNT_ID_LEN
+    ) {
+      return false;
+    }
+
+    // The valid account ID regex is /^(([a-z\d]+[-_])*[a-z\d]+\.)*([a-z\d]+[-_])*[a-z\d]+$/
+
+    // We can safely assume that last char was a separator.
+    var last_char_is_separator = true;
+
+    for (let n = 0; n < accountId.length; n++) {
+      let c = accountId.charAt(n);
+      let current_char_is_separator = c == "-" || c == "_" || c == ".";
+      if (
+        !current_char_is_separator &&
+        !((c >= "a" && c <= "z") || (c >= "0" && c <= "9"))
+      )
+        return false; //only 0..9 a..z and separators are valid chars
+      if (current_char_is_separator && last_char_is_separator) {
+        return false; //do not allow 2 separs together
+      }
+      last_char_is_separator = current_char_is_separator;
+    }
+    // The account can't end as separator.
+    return !last_char_is_separator;
+  }
+
   // #################
   // # Economics API #
   // #################