diff --git a/.gitignore b/.gitignore
index ca55ba5..cda7104 100644
--- a/.gitignore
+++ b/.gitignore
@@ -31,6 +31,7 @@ Thumbs.db
 .ruff_cache/
 .coverage
 htmlcov/
+demo.run.py
 
 # Build & distribution
 dist/
diff --git a/pyfragment/client.py b/pyfragment/client.py
index 677f90a..3618632 100644
--- a/pyfragment/client.py
+++ b/pyfragment/client.py
@@ -58,6 +58,9 @@ class FragmentClient:
         if word_count not in (12, 18, 24):
             raise ConfigurationError(ConfigurationError.INVALID_MNEMONIC.format(count=word_count))
 
+        if len(api_key.strip()) < 68:
+            raise ConfigurationError(ConfigurationError.INVALID_API_KEY.format(length=len(api_key.strip())))
+
         if isinstance(cookies, str):
             try:
                 cookies = json.loads(cookies)
diff --git a/pyfragment/types/exceptions.py b/pyfragment/types/exceptions.py
index b25fdbe..435a50c 100644
--- a/pyfragment/types/exceptions.py
+++ b/pyfragment/types/exceptions.py
@@ -12,6 +12,7 @@ class ConfigurationError(ClientError):
     MISSING_VARS = "Missing required parameter(s): {keys}."
     UNSUPPORTED_VERSION = "Unsupported wallet_version '{version}'. Must be one of: {supported}."
     INVALID_MNEMONIC = "Invalid mnemonic: got {count} words, expected 12, 18, or 24."
+    INVALID_API_KEY = "Invalid Tonapi key: got {length} characters, expected at least 68. Get one at https://tonconsole.com."
     INVALID_MONTHS = "Invalid duration. Choose 3, 6, or 12 months."
     INVALID_STARS_AMOUNT = "Amount must be an integer between 50 and 1 000 000 stars."
     INVALID_TON_AMOUNT = "Amount must be an integer between 1 and 1 000 000 000 TON."
diff --git a/pyfragment/utils/wallet.py b/pyfragment/utils/wallet.py
index 3a8fded..55680f2 100644
--- a/pyfragment/utils/wallet.py
+++ b/pyfragment/utils/wallet.py
@@ -1,7 +1,9 @@
+import asyncio
 import base64
 from typing import TYPE_CHECKING, Any
 
 from tonutils.clients import TonapiClient
+from tonutils.exceptions import ProviderResponseError
 from tonutils.types import NetworkGlobalID
 
 from pyfragment.types import MIN_TON_BALANCE, WALLET_CLASSES, TransactionError, WalletError
@@ -57,12 +59,19 @@ async def process_transaction(client: "FragmentClient", transaction_data: dict)
         try:
             payload = clean_decode(message["payload"])
 
-            result = await wallet.transfer(
-                destination=message["address"],
-                amount=int(message["amount"]),  # nanotons, not TON
-                body=payload,
-            )
-            return result.normalized_hash
+            for attempt in range(2):
+                try:
+                    result = await wallet.transfer(
+                        destination=message["address"],
+                        amount=int(message["amount"]),  # nanotons, not TON
+                        body=payload,
+                    )
+                    return result.normalized_hash
+                except ProviderResponseError as exc:
+                    if exc.code == 429 and attempt == 0:
+                        await asyncio.sleep(1)
+                        continue
+                    raise
         except (WalletError, TransactionError):
             raise
         except Exception as exc:
diff --git a/pyproject.toml b/pyproject.toml
index b96a1f0..1f6ab66 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -27,13 +27,13 @@ classifiers = [
 ]
 dependencies = [
     "httpx==0.28.1",
-    "tonutils[pytoniq]==2.0.0",
+    "tonutils[pytoniq]==2.0.4",
 ]
 
 [project.optional-dependencies]
 dev = [
-    "pytest>=9.0",
-    "pytest-asyncio>=1.0",
+    "pytest==9.0.2",
+    "pytest-asyncio==1.3.0",
     "ruff",
     "black",
 ]
diff --git a/tests/002_test_client.py b/tests/002_test_client.py
index 79b7406..152ae6d 100644
--- a/tests/002_test_client.py
+++ b/tests/002_test_client.py
@@ -8,7 +8,7 @@ from pyfragment import FragmentClient
 from pyfragment.types import ConfigurationError, CookieError
 
 VALID_SEED = "abandon " * 23 + "about"
-VALID_API_KEY = "test_api_key"
+VALID_API_KEY = "A" * 68
 VALID_COOKIES = {
     "stel_ssid": "x",
     "stel_dt": "x",
@@ -92,3 +92,8 @@ def test_valid_mnemonic_lengths() -> None:
         seed = " ".join(["abandon"] * (length - 1) + ["about"])
         client = FragmentClient(seed=seed, api_key=VALID_API_KEY, cookies=VALID_COOKIES)
         assert len(client.seed.split()) == length
+
+
+def test_short_api_key_raises() -> None:
+    with pytest.raises(ConfigurationError):
+        FragmentClient(seed=VALID_SEED, api_key="A" * 42, cookies=VALID_COOKIES)