diff --git a/changelog.d/12355.misc b/changelog.d/12355.misc
new file mode 100644
index 000000000..b1dd1e269
--- /dev/null
+++ b/changelog.d/12355.misc
@@ -0,0 +1 @@
+Remove broken and unused development scripts.
\ No newline at end of file
diff --git a/mypy.ini b/mypy.ini
index 85291099a..ac2a5c753 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -24,11 +24,8 @@ files =
 exclude = (?x)
   ^(
    |scripts-dev/build_debian_packages.py
-   |scripts-dev/definitions.py
    |scripts-dev/federation_client.py
-   |scripts-dev/hash_history.py
    |scripts-dev/release.py
-   |scripts-dev/tail-synapse.py
 
    |synapse/_scripts/export_signing_key.py
    |synapse/_scripts/move_remote_media_to_new_store.py
diff --git a/scripts-dev/definitions.py b/scripts-dev/definitions.py
deleted file mode 100755
index c82ddd967..000000000
--- a/scripts-dev/definitions.py
+++ /dev/null
@@ -1,208 +0,0 @@
-#! /usr/bin/python
-
-import argparse
-import ast
-import os
-import re
-import sys
-
-import yaml
-
-
-class DefinitionVisitor(ast.NodeVisitor):
-    def __init__(self):
-        super().__init__()
-        self.functions = {}
-        self.classes = {}
-        self.names = {}
-        self.attrs = set()
-        self.definitions = {
-            "def": self.functions,
-            "class": self.classes,
-            "names": self.names,
-            "attrs": self.attrs,
-        }
-
-    def visit_Name(self, node):
-        self.names.setdefault(type(node.ctx).__name__, set()).add(node.id)
-
-    def visit_Attribute(self, node):
-        self.attrs.add(node.attr)
-        for child in ast.iter_child_nodes(node):
-            self.visit(child)
-
-    def visit_ClassDef(self, node):
-        visitor = DefinitionVisitor()
-        self.classes[node.name] = visitor.definitions
-        for child in ast.iter_child_nodes(node):
-            visitor.visit(child)
-
-    def visit_FunctionDef(self, node):
-        visitor = DefinitionVisitor()
-        self.functions[node.name] = visitor.definitions
-        for child in ast.iter_child_nodes(node):
-            visitor.visit(child)
-
-
-def non_empty(defs):
-    functions = {name: non_empty(f) for name, f in defs["def"].items()}
-    classes = {name: non_empty(f) for name, f in defs["class"].items()}
-    result = {}
-    if functions:
-        result["def"] = functions
-    if classes:
-        result["class"] = classes
-    names = defs["names"]
-    uses = []
-    for name in names.get("Load", ()):
-        if name not in names.get("Param", ()) and name not in names.get("Store", ()):
-            uses.append(name)
-    uses.extend(defs["attrs"])
-    if uses:
-        result["uses"] = uses
-    result["names"] = names
-    result["attrs"] = defs["attrs"]
-    return result
-
-
-def definitions_in_code(input_code):
-    input_ast = ast.parse(input_code)
-    visitor = DefinitionVisitor()
-    visitor.visit(input_ast)
-    definitions = non_empty(visitor.definitions)
-    return definitions
-
-
-def definitions_in_file(filepath):
-    with open(filepath) as f:
-        return definitions_in_code(f.read())
-
-
-def defined_names(prefix, defs, names):
-    for name, funcs in defs.get("def", {}).items():
-        names.setdefault(name, {"defined": []})["defined"].append(prefix + name)
-        defined_names(prefix + name + ".", funcs, names)
-
-    for name, funcs in defs.get("class", {}).items():
-        names.setdefault(name, {"defined": []})["defined"].append(prefix + name)
-        defined_names(prefix + name + ".", funcs, names)
-
-
-def used_names(prefix, item, defs, names):
-    for name, funcs in defs.get("def", {}).items():
-        used_names(prefix + name + ".", name, funcs, names)
-
-    for name, funcs in defs.get("class", {}).items():
-        used_names(prefix + name + ".", name, funcs, names)
-
-    path = prefix.rstrip(".")
-    for used in defs.get("uses", ()):
-        if used in names:
-            if item:
-                names[item].setdefault("uses", []).append(used)
-            names[used].setdefault("used", {}).setdefault(item, []).append(path)
-
-
-if __name__ == "__main__":
-
-    parser = argparse.ArgumentParser(description="Find definitions.")
-    parser.add_argument(
-        "--unused", action="store_true", help="Only list unused definitions"
-    )
-    parser.add_argument(
-        "--ignore", action="append", metavar="REGEXP", help="Ignore a pattern"
-    )
-    parser.add_argument(
-        "--pattern", action="append", metavar="REGEXP", help="Search for a pattern"
-    )
-    parser.add_argument(
-        "directories",
-        nargs="+",
-        metavar="DIR",
-        help="Directories to search for definitions",
-    )
-    parser.add_argument(
-        "--referrers",
-        default=0,
-        type=int,
-        help="Include referrers up to the given depth",
-    )
-    parser.add_argument(
-        "--referred",
-        default=0,
-        type=int,
-        help="Include referred down to the given depth",
-    )
-    parser.add_argument(
-        "--format", default="yaml", help="Output format, one of 'yaml' or 'dot'"
-    )
-    args = parser.parse_args()
-
-    definitions = {}
-    for directory in args.directories:
-        for root, _, files in os.walk(directory):
-            for filename in files:
-                if filename.endswith(".py"):
-                    filepath = os.path.join(root, filename)
-                    definitions[filepath] = definitions_in_file(filepath)
-
-    names = {}
-    for filepath, defs in definitions.items():
-        defined_names(filepath + ":", defs, names)
-
-    for filepath, defs in definitions.items():
-        used_names(filepath + ":", None, defs, names)
-
-    patterns = [re.compile(pattern) for pattern in args.pattern or ()]
-    ignore = [re.compile(pattern) for pattern in args.ignore or ()]
-
-    result = {}
-    for name, definition in names.items():
-        if patterns and not any(pattern.match(name) for pattern in patterns):
-            continue
-        if ignore and any(pattern.match(name) for pattern in ignore):
-            continue
-        if args.unused and definition.get("used"):
-            continue
-        result[name] = definition
-
-    referrer_depth = args.referrers
-    referrers = set()
-    while referrer_depth:
-        referrer_depth -= 1
-        for entry in result.values():
-            for used_by in entry.get("used", ()):
-                referrers.add(used_by)
-        for name, definition in names.items():
-            if name not in referrers:
-                continue
-            if ignore and any(pattern.match(name) for pattern in ignore):
-                continue
-            result[name] = definition
-
-    referred_depth = args.referred
-    referred = set()
-    while referred_depth:
-        referred_depth -= 1
-        for entry in result.values():
-            for uses in entry.get("uses", ()):
-                referred.add(uses)
-        for name, definition in names.items():
-            if name not in referred:
-                continue
-            if ignore and any(pattern.match(name) for pattern in ignore):
-                continue
-            result[name] = definition
-
-    if args.format == "yaml":
-        yaml.dump(result, sys.stdout, default_flow_style=False)
-    elif args.format == "dot":
-        print("digraph {")
-        for name, entry in result.items():
-            print(name)
-            for used_by in entry.get("used", ()):
-                if used_by in result:
-                    print(used_by, "->", name)
-        print("}")
-    else:
-        raise ValueError("Unknown format %r" % (args.format))
diff --git a/scripts-dev/hash_history.py b/scripts-dev/hash_history.py
deleted file mode 100644
index 8d6c3d24d..000000000
--- a/scripts-dev/hash_history.py
+++ /dev/null
@@ -1,81 +0,0 @@
-import sqlite3
-import sys
-
-from unpaddedbase64 import decode_base64, encode_base64
-
-from synapse.crypto.event_signing import (
-    add_event_pdu_content_hash,
-    compute_pdu_event_reference_hash,
-)
-from synapse.federation.units import Pdu
-from synapse.storage._base import SQLBaseStore
-from synapse.storage.pdu import PduStore
-from synapse.storage.signatures import SignatureStore
-
-
-class Store:
-    _get_pdu_tuples = PduStore.__dict__["_get_pdu_tuples"]
-    _get_pdu_content_hashes_txn = SignatureStore.__dict__["_get_pdu_content_hashes_txn"]
-    _get_prev_pdu_hashes_txn = SignatureStore.__dict__["_get_prev_pdu_hashes_txn"]
-    _get_pdu_origin_signatures_txn = SignatureStore.__dict__[
-        "_get_pdu_origin_signatures_txn"
-    ]
-    _store_pdu_content_hash_txn = SignatureStore.__dict__["_store_pdu_content_hash_txn"]
-    _store_pdu_reference_hash_txn = SignatureStore.__dict__[
-        "_store_pdu_reference_hash_txn"
-    ]
-    _store_prev_pdu_hash_txn = SignatureStore.__dict__["_store_prev_pdu_hash_txn"]
-    simple_insert_txn = SQLBaseStore.__dict__["simple_insert_txn"]
-
-
-store = Store()
-
-
-def select_pdus(cursor):
-    cursor.execute("SELECT pdu_id, origin FROM pdus ORDER BY depth ASC")
-
-    ids = cursor.fetchall()
-
-    pdu_tuples = store._get_pdu_tuples(cursor, ids)
-
-    pdus = [Pdu.from_pdu_tuple(p) for p in pdu_tuples]
-
-    reference_hashes = {}
-
-    for pdu in pdus:
-        try:
-            if pdu.prev_pdus:
-                print("PROCESS", pdu.pdu_id, pdu.origin, pdu.prev_pdus)
-                for pdu_id, origin, hashes in pdu.prev_pdus:
-                    ref_alg, ref_hsh = reference_hashes[(pdu_id, origin)]
-                    hashes[ref_alg] = encode_base64(ref_hsh)
-                    store._store_prev_pdu_hash_txn(
-                        cursor, pdu.pdu_id, pdu.origin, pdu_id, origin, ref_alg, ref_hsh
-                    )
-                print("SUCCESS", pdu.pdu_id, pdu.origin, pdu.prev_pdus)
-            pdu = add_event_pdu_content_hash(pdu)
-            ref_alg, ref_hsh = compute_pdu_event_reference_hash(pdu)
-            reference_hashes[(pdu.pdu_id, pdu.origin)] = (ref_alg, ref_hsh)
-            store._store_pdu_reference_hash_txn(
-                cursor, pdu.pdu_id, pdu.origin, ref_alg, ref_hsh
-            )
-
-            for alg, hsh_base64 in pdu.hashes.items():
-                print(alg, hsh_base64)
-                store._store_pdu_content_hash_txn(
-                    cursor, pdu.pdu_id, pdu.origin, alg, decode_base64(hsh_base64)
-                )
-
-        except Exception:
-            print("FAILED_", pdu.pdu_id, pdu.origin, pdu.prev_pdus)
-
-
-def main():
-    conn = sqlite3.connect(sys.argv[1])
-    cursor = conn.cursor()
-    select_pdus(cursor)
-    conn.commit()
-
-
-if __name__ == "__main__":
-    main()
diff --git a/scripts-dev/tail-synapse.py b/scripts-dev/tail-synapse.py
deleted file mode 100644
index 44e3a6dbf..000000000
--- a/scripts-dev/tail-synapse.py
+++ /dev/null
@@ -1,67 +0,0 @@
-import collections
-import json
-import sys
-import time
-
-import requests
-
-Entry = collections.namedtuple("Entry", "name position rows")
-
-ROW_TYPES = {}
-
-
-def row_type_for_columns(name, column_names):
-    column_names = tuple(column_names)
-    row_type = ROW_TYPES.get((name, column_names))
-    if row_type is None:
-        row_type = collections.namedtuple(name, column_names)
-        ROW_TYPES[(name, column_names)] = row_type
-    return row_type
-
-
-def parse_response(content):
-    streams = json.loads(content)
-    result = {}
-    for name, value in streams.items():
-        row_type = row_type_for_columns(name, value["field_names"])
-        position = value["position"]
-        rows = [row_type(*row) for row in value["rows"]]
-        result[name] = Entry(name, position, rows)
-    return result
-
-
-def replicate(server, streams):
-    return parse_response(
-        requests.get(
-            server + "/_synapse/replication", verify=False, params=streams
-        ).content
-    )
-
-
-def main():
-    server = sys.argv[1]
-
-    streams = None
-    while not streams:
-        try:
-            streams = {
-                row.name: row.position
-                for row in replicate(server, {"streams": "-1"})["streams"].rows
-            }
-        except requests.exceptions.ConnectionError:
-            time.sleep(0.1)
-
-    while True:
-        try:
-            results = replicate(server, streams)
-        except Exception:
-            sys.stdout.write("connection_lost(" + repr(streams) + ")\n")
-            break
-        for update in results.values():
-            for row in update.rows:
-                sys.stdout.write(repr(row) + "\n")
-            streams[update.name] = update.position
-
-
-if __name__ == "__main__":
-    main()