diff --git a/ephemetoot/ephemetoot.py b/ephemetoot/ephemetoot.py
index b456f8b..9615e2a 100644
--- a/ephemetoot/ephemetoot.py
+++ b/ephemetoot/ephemetoot.py
@@ -2,6 +2,7 @@
 from datetime import date, datetime, timedelta, timezone
 import json
 import os
+import re
 import subprocess
 import sys
 import time
@@ -29,7 +30,14 @@ def compulsory_input(tags, name, example):
         else:
             value = input(tags[0] + name + tags[2])
 
-    return value
+        sanitised = sanitise_input(value, name, tags)
+
+        if len(value) > 0 and (sanitised == "ok" or sanitised == None):
+            return value
+        else:
+            if len(value) > 0 and sanitised != None:
+                print(sanitised)
+            value = ""
 
 
 def digit_input(tags, name, example):
@@ -53,8 +61,108 @@ def yes_no_input(tags, name):
 
 
 def optional_input(tags, name, example):
-    value = input(tags[0] + name + tags[1] + example + tags[2])
-    return value
+
+    incomplete = True
+    while incomplete:
+        value = input(tags[0] + name + tags[1] + example + tags[2])
+        sanitised = sanitise_input(value, name, tags)
+        if len(value) > 0 and (sanitised == "ok" or sanitised == None):
+            incomplete = False
+            return value
+        elif len(value) > 0 and sanitised != None:
+            print(sanitised)
+        else:
+            return ""
+
+
+def sanitise_input(value, input_type, tags):
+    """
+    Check that data entered when running --init complies with requirements
+    """
+
+    if input_type == "Username":
+        return (
+            "Do not include '@' in username, please try again"
+            if value.startswith("@")
+            else "ok"
+        )
+
+    if input_type == "Base URL":
+        error = value.startswith("http") or value.find(".") == -1
+        return (
+            "Provide full domain without protocol prefix (e.g. "
+            + tags[1]
+            + "example.social"
+            + tags[2]
+            + ", not "
+            + tags[1]
+            + "http://example.social"
+            + tags[2]
+            + ")"
+            if error
+            else "ok"
+        )
+
+    if input_type == "Toots to keep":
+        l = value.split(",")
+
+        def check(s):
+            d = s.strip()
+            if not d.isdigit():
+                return False
+
+        allnum = map(check, l)
+        return (
+            "Toot IDs must be numeric and separated with commas"
+            if False in list(allnum)
+            else "ok"
+        )
+
+    if input_type == "Hashtags to keep":
+        l = value.split(",")
+
+        def check(s):
+            d = s.strip()
+            if d.isdigit():
+                return False
+            if not re.fullmatch(r"[\w]+", d, flags=re.IGNORECASE):
+                return False
+
+        complies = map(check, l)
+        return_string = (
+            "Hashtags must not include '#' and must match rules at "
+            + tags[0]
+            + "https://docs.joinmastodon.org/user/posting/#hashtags"
+            + tags[2]
+        )
+        return return_string if False in list(complies) else "ok"
+
+    if input_type == "Visibility to keep":
+        l = value.split(",")
+        viz_options = set(["public", "unlisted", "private", "direct"])
+
+        def check(s):
+            d = [s.strip().lower()]
+            intersects = viz_options.intersection(d)
+            if len(intersects) == 0:
+                return False
+
+        complies = map(check, l)
+        return_string = "Valid values are one or more of 'public', 'unlisted', 'private' or 'direct'"
+        return return_string if False in list(complies) else "ok"
+
+    if input_type == "Archive path":
+        path = (
+            os.path.expanduser(value)
+            if len(str(value)) > 0 and str(value)[0] == "~"
+            else value
+        )
+        response = (
+            "ok"
+            if os.path.exists(path)
+            else "That directory does not exist, please try again"
+        )
+        return response
 
 
 def init():
diff --git a/tests/test_ephemetoot.py b/tests/test_ephemetoot.py
index 6e684a9..a13cef2 100644
--- a/tests/test_ephemetoot.py
+++ b/tests/test_ephemetoot.py
@@ -291,6 +291,94 @@ def test_init(monkeypatch, tmpdir):
     assert os.path.exists(os.path.join(current_dir, "config.yaml"))
 
 
+def test_init_archive_path(tmpdir):
+
+    good_path = tmpdir.mkdir("archive_dir")  # temporary directory for testing
+    wrong = ephemetoot.sanitise_input(
+        os.path.join(good_path, "/bad/path/"), "Archive path", None
+    )
+    ok = ephemetoot.sanitise_input(good_path, "Archive path", None)
+    also_ok = ephemetoot.sanitise_input("~/Desktop", "Archive path", None)
+
+    assert ok == "ok"
+    assert wrong == "That directory does not exist, please try again"
+
+
+def test_init_sanitise_id_list():
+    tags = ("\033[96m", "\033[2m", "\033[0m")
+    wrong = ephemetoot.sanitise_input(
+        "987654321, toot_id_number", "Toots to keep", tags
+    )
+    also_wrong = ephemetoot.sanitise_input("toot_id_number", "Toots to keep", tags)
+    ok = ephemetoot.sanitise_input("1234598745, 999933335555", "Toots to keep", tags)
+    also_ok = ephemetoot.sanitise_input("1234598745", "Toots to keep", tags)
+
+    assert wrong == "Toot IDs must be numeric and separated with commas"
+    assert also_wrong == "Toot IDs must be numeric and separated with commas"
+    assert ok == "ok"
+    assert also_ok == "ok"
+
+
+def test_init_sanitise_tag_list():
+    tags = ("\033[96m", "\033[2m", "\033[0m")
+    wrong = ephemetoot.sanitise_input("#tag, another_tag", "Hashtags to keep", tags)
+    also_wrong = ephemetoot.sanitise_input("tag, another tag", "Hashtags to keep", tags)
+    still_wrong = ephemetoot.sanitise_input("tag, 12345", "Hashtags to keep", tags)
+    ok = ephemetoot.sanitise_input("tag123, another_TAG", "Hashtags to keep", tags)
+    also_ok = ephemetoot.sanitise_input("single_tag", "Hashtags to keep", tags)
+
+    error = (
+        "Hashtags must not include '#' and must match rules at "
+        + tags[0]
+        + "https://docs.joinmastodon.org/user/posting/#hashtags"
+        + tags[2]
+    )
+
+    assert ok == "ok"
+    assert also_ok == "ok"
+    assert wrong == error
+    assert also_wrong == error
+    assert still_wrong == error
+
+
+def test_init_sanitise_url():
+    tags = ("\033[96m", "\033[2m", "\033[0m")
+    wrong = ephemetoot.sanitise_input("http://example.social", "Base URL", tags)
+    also_wrong = ephemetoot.sanitise_input("http://example.social", "Base URL", tags)
+    ok = ephemetoot.sanitise_input("example.social", "Base URL", tags)
+
+    assert (
+        wrong
+        == "Provide full domain without protocol prefix (e.g. \033[2mexample.social\033[0m, not \033[2mhttp://example.social\033[0m)"
+    )
+    assert ok == "ok"
+
+
+def test_init_sanitise_username():
+    tags = ("\033[96m", "\033[2m", "\033[0m")
+    wrong = ephemetoot.sanitise_input("@alice", "Username", tags)
+    ok = ephemetoot.sanitise_input("alice", "Username", tags)
+
+    assert wrong == "Do not include '@' in username, please try again"
+    assert ok == "ok"
+
+
+def test_init_sanitise_visibility_list():
+    tags = ("\033[96m", "\033[2m", "\033[0m")
+    wrong = ephemetoot.sanitise_input("nonexistent", "Visibility to keep", tags)
+    also_wrong = ephemetoot.sanitise_input("direct public", "Visibility to keep", tags)
+    ok = ephemetoot.sanitise_input("direct", "Visibility to keep", tags)
+    also_ok = ephemetoot.sanitise_input("direct, public", "Visibility to keep", tags)
+
+    error = (
+        "Valid values are one or more of 'public', 'unlisted', 'private' or 'direct'"
+    )
+    assert ok == "ok"
+    assert also_ok == "ok"
+    assert wrong == error
+    assert also_wrong == error
+
+
 def test_jsondefault():
     d = ephemetoot.jsondefault(toot.created_at)
     assert d == "2020-05-09T02:17:18.598000+00:00"