diff --git a/public/locales/en.json b/public/locales/en.json
index 7b8a896..bf133f9 100644
--- a/public/locales/en.json
+++ b/public/locales/en.json
@@ -728,7 +728,7 @@
   "optionalFieldUnset": "(unset)",
 
   "addressPicker": {
-    "placeholder": "Type an address, or choose a wallet",
+    "placeholder": "Choose a recipient",
     "placeholderWalletsOnly": "Choose a wallet",
 
     "hintCurrentBalance": "Current balance: <1 />",
@@ -766,7 +766,15 @@
     "labelMetadata": "Metadata",
     "placeholderMetadata": "Optional metadata",
 
-    "buttonMax": "Max"
+    "buttonMax": "Max",
+
+    "errorAmountRequired": "Amount is required.",
+    "errorAmountNumber": "Amount must be a number.",
+    "errorAmountTooLow": "Amount must be at least 1.",
+    "errorAmountTooHigh": "Insufficient funds in wallet.",
+
+    "errorMetadataTooLong": "Metadata must be less than 256 characters.",
+    "errorMetadataInvalid": "Metadata contains invalid characters."
 
     // TODO: modals/warnings for confirmation of sending over 50% of balance,
     //       whole balance, and form validation messages
diff --git a/public/locales/nl.json b/public/locales/nl.json
index 036c432..706d9cc 100644
--- a/public/locales/nl.json
+++ b/public/locales/nl.json
@@ -727,7 +727,7 @@
   "optionalFieldUnset": "(geen waarde)",
 
   "addressPicker": {
-    "placeholder": "Typ een adres of kies een wallet",
+    "placeholder": "Kies een ontvanger",
     "placeholderWalletsOnly": "Kies een wallet",
 
     "hintCurrentBalance": "Huidige balans: <1 />",
diff --git a/src/components/addresses/picker/AddressPicker.tsx b/src/components/addresses/picker/AddressPicker.tsx
index 5bd5b39..faf8928 100644
--- a/src/components/addresses/picker/AddressPicker.tsx
+++ b/src/components/addresses/picker/AddressPicker.tsx
@@ -169,6 +169,7 @@
     >
       <AutoComplete
         dropdownClassName="address-picker-dropdown"
+        dropdownMatchSelectWidth={false}
 
         // Change the placeholder to 'Choose a wallet' if applicable
         placeholder={walletsOnly
diff --git a/src/pages/transactions/send/AmountInput.tsx b/src/pages/transactions/send/AmountInput.tsx
new file mode 100644
index 0000000..53df896
--- /dev/null
+++ b/src/pages/transactions/send/AmountInput.tsx
@@ -0,0 +1,89 @@
+// Copyright (c) 2020-2021 Drew Lemmy
+// This file is part of KristWeb 2 under GPL-3.0.
+// Full details: https://github.com/tmpim/KristWeb2/blob/master/LICENSE.txt
+import { Form, Input, InputNumber, Button } from "antd";
+
+import { useTranslation } from "react-i18next";
+
+import { useWallets } from "@wallets";
+import { useCurrency } from "@utils/currency";
+
+import { KristSymbol } from "@comp/krist/KristSymbol";
+
+interface Props {
+  from: string;
+  setValue: (value: number) => void;
+}
+
+export function AmountInput({ from, setValue, ...props }: Props): JSX.Element {
+  const { t } = useTranslation();
+
+  // Used to populate 'Max'
+  const { walletAddressMap } = useWallets();
+
+  // Used to format the currency prefix/suffix
+  const { currency_symbol } = useCurrency();
+
+  function onClickMax() {
+    const currentWallet = walletAddressMap[from];
+    setValue(currentWallet?.balance || 0);
+  }
+
+  return <Form.Item
+    label={t("sendTransaction.labelValue")}
+    required
+    {...props}
+  >
+    <Input.Group compact style={{ display: "flex" }}>
+      {/* Prepend the Krist symbol if possible. Note that ant's InputNumber
+        * doesn't support addons, so this has to be done manually. */}
+      {(currency_symbol || "KST") === "KST" && (
+        <span className="ant-input-group-addon currency-prefix">
+          <KristSymbol />
+        </span>
+      )}
+
+      {/* Value/amount number input */}
+      <Form.Item
+        name="value"
+        style={{ flex: 1, marginBottom: 0 }}
+
+        validateFirst
+        rules={[
+          { required: true, message: t("sendTransaction.errorAmountRequired") },
+          { type: "number", message: t("sendTransaction.errorAmountNumber") },
+
+          // Validate that the number isn't higher than the selected wallet's
+          // balance
+          {
+            async validator(_, value): Promise<void> {
+              if (value < 1)
+                throw t("sendTransaction.errorAmountTooLow");
+
+              const currentWallet = walletAddressMap[from];
+              if (!currentWallet) return;
+              if (value > (currentWallet.balance || 0))
+                throw t("sendTransaction.errorAmountTooHigh");
+            }
+          },
+        ]}
+      >
+        <InputNumber
+          type="number"
+          min={1}
+          style={{ width: "100%", height: 32 }}
+        />
+      </Form.Item>
+
+      {/* Currency suffix */}
+      <span className="ant-input-group-addon">
+        {currency_symbol || "KST"}
+      </span>
+
+      {/* Max value button */}
+      <Button onClick={onClickMax}>
+        {t("sendTransaction.buttonMax")}
+      </Button>
+    </Input.Group>
+  </Form.Item>;
+}
diff --git a/src/pages/transactions/send/SendTransactionForm.less b/src/pages/transactions/send/SendTransactionForm.less
new file mode 100644
index 0000000..95ae29f
--- /dev/null
+++ b/src/pages/transactions/send/SendTransactionForm.less
@@ -0,0 +1,22 @@
+// Copyright (c) 2020-2021 Drew Lemmy
+// This file is part of KristWeb 2 under GPL-3.0.
+// Full details: https://github.com/tmpim/KristWeb2/blob/master/LICENSE.txt
+@import (reference) "../../../App.less";
+
+.send-transaction-form {
+  .ant-input-group-addon {
+    border: none;
+    flex: 0;
+    width: auto;
+    vertical-align: middle;
+    line-height: @input-height-base;
+    height: @input-height-base;
+
+    &.currency-prefix .anticon {
+      color: @kw-text-tertiary;
+      font-size: 80%;
+      vertical-align: middle;
+      line-height: @input-height-base;
+    }
+  }
+}
diff --git a/src/pages/transactions/send/SendTransactionForm.tsx b/src/pages/transactions/send/SendTransactionForm.tsx
index 826eb08..ebc460d 100644
--- a/src/pages/transactions/send/SendTransactionForm.tsx
+++ b/src/pages/transactions/send/SendTransactionForm.tsx
@@ -1,17 +1,21 @@
 // Copyright (c) 2020-2021 Drew Lemmy
 // This file is part of KristWeb 2 under GPL-3.0.
 // Full details: https://github.com/tmpim/KristWeb2/blob/master/LICENSE.txt
-import React, { useState } from "react";
-import { Form, FormInstance, Input, InputNumber, Button } from "antd";
+import { useState } from "react";
+import { Row, Col, Form, FormInstance, Input } from "antd";
 
 import { useTranslation } from "react-i18next";
 
 import { useWallets } from "@wallets";
-import { useCurrency } from "@utils/currency";
 
 import { AddressPicker } from "@comp/addresses/picker/AddressPicker";
+import { AmountInput } from "./AmountInput";
 
-import { KristSymbol } from "@comp/krist/KristSymbol";
+import "./SendTransactionForm.less";
+
+// This is from https://github.com/tmpim/Krist/blob/a924f3f/src/controllers/transactions.js#L102
+// except `+` is changed to `*`.
+const METADATA_REGEXP = /^[\x20-\x7F\n]*$/i;
 
 export interface FormValues {
   from: string;
@@ -33,15 +37,12 @@
 
   // Used to get the initial wallet to show for the 'from' field
   // TODO: Remember this value?
-  const { addressList, walletAddressMap } = useWallets();
+  const { addressList } = useWallets();
   const initialFrom = addressList[0] || "";
   // TODO: initialFrom here should never be an empty string, so need to add a
   //       modal that says "You currently don't have any saved wallets" etc,
   //       and prevents opening the sendTX modal/rendering the page
 
-  // Used to format the 'amount' field
-  const { currency_symbol } = useCurrency();
-
   const [from, setFrom] = useState(initialFrom);
   const [to, setTo] = useState("");
 
@@ -57,6 +58,7 @@
     // `useTransactionForm` hook.
     form={form}
     layout="vertical"
+    className="send-transaction-form"
 
     name="sendTransaction"
 
@@ -70,46 +72,49 @@
     onValuesChange={onValuesChange}
     onFinish={triggerSubmit}
   >
-    {/* From */}
-    <AddressPicker
-      walletsOnly
-      name="from"
-      label={t("sendTransaction.labelFrom")}
-      value={from}
-    />
+    <Row gutter={16}>
+      {/* From */}
+      <Col span={24} md={12}>
+        <AddressPicker
+          walletsOnly
+          name="from"
+          label={t("sendTransaction.labelFrom")}
+          value={from}
+        />
+      </Col>
 
-    {/* To */}
-    <AddressPicker
-      name="to"
-      label={t("sendTransaction.labelTo")}
-      value={to}
-      otherPickerValue={from === undefined ? initialFrom : from}
-    />
+      {/* To */}
+      <Col span={24} md={12}>
+        <AddressPicker
+          name="to"
+          label={t("sendTransaction.labelTo")}
+          value={to}
+          otherPickerValue={from === undefined ? initialFrom : from}
+        />
+      </Col>
+    </Row>
 
     {/* Amount */}
-    <Form.Item label={t("sendTransaction.labelValue")}>
-      <Input.Group compact style={{ display: "flex" }}>
-        {/* Prepend the Krist symbol if possible. Note that ant's InputNumber
-          * doesn't support addons, so this has to be done manually. */}
-        {(currency_symbol || "KST") === "KST" && (
-          <span className="ant-input-group-addon"><KristSymbol /></span>
-        )}
+    <AmountInput
+      from={from === undefined ? initialFrom : from}
+      setValue={value => form.setFieldsValue({ value })}
+    />
 
-        {/* Value/amount number input */}
-        <Form.Item
-          name="value"
-          style={{ flex: 1, marginBottom: 0 }}
-        >
-          <InputNumber
-            type="number"
-            min={1}
-            style={{ width: "100%", height: 32 }}
-          />
-        </Form.Item>
-
-        {/* Max value button */}
-        <Button>{t("sendTransaction.buttonMax")}</Button>
-      </Input.Group>
+    {/* Metadata */}
+    <Form.Item
+      name="metadata"
+      label={t("sendTransaction.labelMetadata")}
+      rules={[
+        { max: 255, message: t("sendTransaction.errorMetadataTooLong") },
+        { pattern: METADATA_REGEXP,
+          message: t("sendTransaction.errorMetadataInvalid") },
+      ]}
+    >
+      <Input.TextArea
+        className="input-monospace"
+        rows={3}
+        placeholder={t("sendTransaction.placeholderMetadata")}
+      />
     </Form.Item>
   </Form>;
 }