diff --git a/tools/gen_crt_bundle.py b/tools/gen_crt_bundle.py
new file mode 100755
index 0000000000..87e29e61fa
--- /dev/null
+++ b/tools/gen_crt_bundle.py
@@ -0,0 +1,227 @@
+#!/usr/bin/env python
+#
+# ESP32 x509 certificate bundle generation utility
+#
+# Converts PEM and DER certificates to a custom bundle format which stores just the
+# subject name and public key to reduce space
+#
+# The bundle will have the format: number of certificates; crt 1 subject name length; crt 1 public key length;
+# crt 1 subject name; crt 1 public key; crt 2...
+#
+# Copyright 2018-2019 Espressif Systems (Shanghai) PTE LTD
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http:#www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import with_statement
+
+import argparse
+import csv
+import os
+import re
+import struct
+import sys
+from io import open
+
+try:
+    from cryptography import x509
+    from cryptography.hazmat.backends import default_backend
+    from cryptography.hazmat.primitives import serialization
+except ImportError:
+    print('The cryptography package is not installed.'
+          'Please refer to the Get Started section of the ESP-IDF Programming Guide for '
+          'setting up the required packages.')
+    raise
+
+ca_bundle_bin_file = 'x509_crt_bundle'
+
+quiet = False
+
+
+def status(msg):
+    """ Print status message to stderr """
+    if not quiet:
+        critical(msg)
+
+
+def critical(msg):
+    """ Print critical message to stderr """
+    sys.stderr.write('gen_crt_bundle.py: ')
+    sys.stderr.write(msg)
+    sys.stderr.write('\n')
+
+
+class CertificateBundle:
+    def __init__(self):
+        self.certificates = []
+        self.compressed_crts = []
+
+        if os.path.isfile(ca_bundle_bin_file):
+            os.remove(ca_bundle_bin_file)
+
+    def add_from_path(self, crts_path):
+
+        found = False
+        for file_path in os.listdir(crts_path):
+            found |= self.add_from_file(os.path.join(crts_path, file_path))
+
+        if found is False:
+            raise InputError('No valid x509 certificates found in %s' % crts_path)
+
+    def add_from_file(self, file_path):
+        try:
+            if file_path.endswith('.pem'):
+                status('Parsing certificates from %s' % file_path)
+                with open(file_path, 'r', encoding='utf-8') as f:
+                    crt_str = f.read()
+                    self.add_from_pem(crt_str)
+                    return True
+
+            elif file_path.endswith('.der'):
+                status('Parsing certificates from %s' % file_path)
+                with open(file_path, 'rb') as f:
+                    crt_str = f.read()
+                    self.add_from_der(crt_str)
+                    return True
+
+        except ValueError:
+            critical('Invalid certificate in %s' % file_path)
+            raise InputError('Invalid certificate')
+
+        return False
+
+    def add_from_pem(self, crt_str):
+        """ A single PEM file may have multiple certificates """
+
+        crt = ''
+        count = 0
+        start = False
+
+        for strg in crt_str.splitlines(True):
+            if strg == '-----BEGIN CERTIFICATE-----\n' and start is False:
+                crt = ''
+                start = True
+            elif strg == '-----END CERTIFICATE-----\n' and start is True:
+                crt += strg + '\n'
+                start = False
+                self.certificates.append(x509.load_pem_x509_certificate(crt.encode(), default_backend()))
+                count += 1
+            if start is True:
+                crt += strg
+
+        if(count == 0):
+            raise InputError('No certificate found')
+
+        status('Successfully added %d certificates' % count)
+
+    def add_from_der(self, crt_str):
+        self.certificates.append(x509.load_der_x509_certificate(crt_str, default_backend()))
+        status('Successfully added 1 certificate')
+
+    def create_bundle(self):
+        # Sort certificates in order to do binary search when looking up certificates
+        self.certificates = sorted(self.certificates, key=lambda cert: cert.subject.public_bytes(default_backend()))
+
+        bundle = struct.pack('>H', len(self.certificates))
+
+        for crt in self.certificates:
+            """ Read the public key as DER format """
+            pub_key = crt.public_key()
+            pub_key_der = pub_key.public_bytes(serialization.Encoding.DER, serialization.PublicFormat.SubjectPublicKeyInfo)
+
+            """ Read the subject name as DER format """
+            sub_name_der = crt.subject.public_bytes(default_backend())
+
+            name_len = len(sub_name_der)
+            key_len = len(pub_key_der)
+            len_data = struct.pack('>HH', name_len, key_len)
+
+            bundle += len_data
+            bundle += sub_name_der
+            bundle += pub_key_der
+
+        return bundle
+
+    def add_with_filter(self, crts_path, filter_path):
+
+        filter_set = set()
+        with open(filter_path, 'r', encoding='utf-8') as f:
+            csv_reader = csv.reader(f, delimiter=',')
+
+            # Skip header
+            next(csv_reader)
+            for row in csv_reader:
+                filter_set.add(row[1])
+
+        status('Parsing certificates from %s' % crts_path)
+        crt_str = []
+        with open(crts_path, 'r', encoding='utf-8') as f:
+            crt_str = f.read()
+
+            # Split all certs into a list of (name, certificate string) tuples
+            pem_crts = re.findall(r'(^.+?)\n(=+\n[\s\S]+?END CERTIFICATE-----\n)', crt_str, re.MULTILINE)
+
+            filtered_crts = ''
+            for name, crt in pem_crts:
+                if name in filter_set:
+                    filtered_crts += crt
+
+        self.add_from_pem(filtered_crts)
+
+
+class InputError(RuntimeError):
+    def __init__(self, e):
+        super(InputError, self).__init__(e)
+
+
+def main():
+    global quiet
+
+    parser = argparse.ArgumentParser(description='ESP-IDF x509 certificate bundle utility')
+
+    parser.add_argument('--quiet', '-q', help="Don't print non-critical status messages to stderr", action='store_true')
+    parser.add_argument('--input', '-i', nargs='+', required=True,
+                        help='Paths to the custom certificate folders or files to parse, parses all .pem or .der files')
+    parser.add_argument('--filter', '-f', help='Path to CSV-file where the second columns contains the name of the certificates \
+                        that should be included from cacrt_all.pem')
+
+    args = parser.parse_args()
+
+    quiet = args.quiet
+
+    bundle = CertificateBundle()
+
+    for path in args.input:
+        if os.path.isfile(path):
+            if os.path.basename(path) == 'cacrt_all.pem' and args.filter:
+                bundle.add_with_filter(path, args.filter)
+            else:
+                bundle.add_from_file(path)
+        elif os.path.isdir(path):
+            bundle.add_from_path(path)
+        else:
+            raise InputError('Invalid --input=%s, is neither file nor folder' % args.input)
+
+    status('Successfully added %d certificates in total' % len(bundle.certificates))
+
+    crt_bundle = bundle.create_bundle()
+
+    with open(ca_bundle_bin_file, 'wb') as f:
+        f.write(crt_bundle)
+
+
+if __name__ == '__main__':
+    try:
+        main()
+    except InputError as e:
+        print(e)
+        sys.exit(2)