As of 2021, the top 10 tech companies with the highest revenue globally are:

1. Apple Inc.
2. Samsung Electronics Co., Ltd.
3. Alphabet Inc. (Google)
4. Microsoft Corporation
5. Amazon.com, Inc.
6. Facebook, Inc.
7. Tencent Holdings Limited
8. Alibaba Group Holding Limited
9. Huawei Technologies Co., Ltd.
10. Sony Corporation

Please note that revenue rankings may vary depending on the time period and fluctuations in financial performances.