---
toc_priority: 71
toc_title: Third-Party Libraries Used
---

# Third-Party Libraries Used {#third-party-libraries-used}

The list of third-party libraries:

| Library name | License type |
|:-|:-|
| abseil-cpp | [Apache](https://github.com/ClickHouse-Extras/abseil-cpp/blob/4f3b686f86c3ebaba7e4e926e62a79cb1c659a54/LICENSE) |
| AMQP-CPP | [Apache](https://github.com/ClickHouse-Extras/AMQP-CPP/blob/1a6c51f4ac51ac56610fa95081bd2f349911375a/LICENSE) |
| arrow | [Apache](https://github.com/ClickHouse-Extras/arrow/blob/078e21bad344747b7656ef2d7a4f7410a0a303eb/LICENSE.txt) |
| avro | [Apache](https://github.com/ClickHouse-Extras/avro/blob/e43c46e87fd32eafdc09471e95344555454c5ef8/LICENSE.txt) |
| aws | [Apache](https://github.com/ClickHouse-Extras/aws-sdk-cpp/blob/7d48b2c8193679cc4516e5bd68ae4a64b94dae7d/LICENSE.txt) |
| aws-c-common | [Apache](https://github.com/ClickHouse-Extras/aws-c-common/blob/736a82d1697c108b04a277e66438a7f4e19b6857/LICENSE) |
| aws-c-event-stream | [Apache](https://github.com/ClickHouse-Extras/aws-c-event-stream/blob/3bc33662f9ccff4f4cbcf9509cc78c26e022fde0/LICENSE) |
| aws-checksums | [Apache](https://github.com/ClickHouse-Extras/aws-checksums/blob/519d6d9093819b6cf89ffff589a27ef8f83d0f65/LICENSE) |
| base64 | [BSD 2-clause](https://github.com/ClickHouse-Extras/Turbo-Base64/blob/af9b331f2b4f30b41c70f3a571ff904a8251c1d3/LICENSE) |
| boost | [Boost](https://github.com/ClickHouse-Extras/boost/blob/9cf09dbfd55a5c6202dedbdf40781a51b02c2675/LICENSE_1_0.txt) |
| boringssl | [BSD](https://github.com/ClickHouse-Extras/boringssl/blob/a6a2e2ab3e44d97ce98e51c558e989f211de7eb3/LICENSE) |
| brotli | [MIT](https://github.com/google/brotli/blob/63be8a99401992075c23e99f7c84de1c653e39e2/LICENSE) |
| capnproto | [MIT](https://github.com/capnproto/capnproto/blob/a00ccd91b3746ef2ab51d40fe3265829949d1ace/LICENSE) |
| cassandra | [Apache](https://github.com/ClickHouse-Extras/cpp-driver/blob/eb9b68dadbb4417a2c132ad4a1c2fa76e65e6fc1/LICENSE.txt) |
| cctz | [Apache](https://github.com/ClickHouse-Extras/cctz/blob/c0f1bcb97fd2782f7c3f972fadd5aad5affac4b8/LICENSE.txt) |
| cityhash102 | [MIT](https://github.com/ClickHouse/ClickHouse/blob/master/contrib/cityhash102/COPYING) |
| cppkafka | [BSD 2-clause](https://github.com/mfontanini/cppkafka/blob/5a119f689f8a4d90d10a9635e7ee2bee5c127de1/LICENSE) |
| croaring | [Apache](https://github.com/RoaringBitmap/CRoaring/blob/2c867e9f9c9e2a3a7032791f94c4c7ae3013f6e0/LICENSE) |
| curl | [Apache](https://github.com/curl/curl/blob/3b8bbbbd1609c638a3d3d0acb148a33dedb67be3/docs/LICENSE-MIXING.md) |
| cyrus-sasl | [BSD 2-clause](https://github.com/ClickHouse-Extras/cyrus-sasl/blob/e6466edfd638cc5073debe941c53345b18a09512/COPYING) |
| double-conversion | [BSD 3-clause](https://github.com/google/double-conversion/blob/cf2f0f3d547dc73b4612028a155b80536902ba02/LICENSE) |
| dragonbox | [Apache](https://github.com/ClickHouse-Extras/dragonbox/blob/923705af6fd953aa948fc175f6020b15f7359838/LICENSE-Apache2-LLVM) |
| fast_float | [Apache](https://github.com/fastfloat/fast_float/blob/7eae925b51fd0f570ccd5c880c12e3e27a23b86f/LICENSE) |
| fastops | [MIT](https://github.com/ClickHouse-Extras/fastops/blob/88752a5e03cf34639a4a37a4b41d8b463fffd2b5/LICENSE) |
| flatbuffers | [Apache](https://github.com/ClickHouse-Extras/flatbuffers/blob/eb3f827948241ce0e701516f16cd67324802bce9/LICENSE.txt) |
| fmtlib | [Unknown](https://github.com/fmtlib/fmt/blob/c108ee1d590089ccf642fc85652b845924067af2/LICENSE.rst) |
| gcem | [Apache](https://github.com/kthohr/gcem/blob/8d4f1b5d76ea8f6ff12f3f4f34cda45424556b00/LICENSE) |
| googletest | [BSD 3-clause](https://github.com/google/googletest/blob/e7e591764baba0a0c3c9ad0014430e7a27331d16/LICENSE) |
| grpc | [Apache](https://github.com/ClickHouse-Extras/grpc/blob/60c986e15cae70aade721d26badabab1f822fdd6/LICENSE) |
| h3 | [Apache](https://github.com/ClickHouse-Extras/h3/blob/c7f46cfd71fb60e2fefc90e28abe81657deff735/LICENSE) |
| hyperscan | [Boost](https://github.com/ClickHouse-Extras/hyperscan/blob/e9f08df0213fc637aac0a5bbde9beeaeba2fe9fa/LICENSE) |
| icu | [Public Domain](https://github.com/unicode-org/icu/blob/a56dde820dc35665a66f2e9ee8ba58e75049b668/icu4c/LICENSE) |
| icudata | [Public Domain](https://github.com/ClickHouse-Extras/icudata/blob/72d9a4a7febc904e2b0a534ccb25ae40fac5f1e5/LICENSE) |
| jemalloc | [BSD 2-clause](https://github.com/ClickHouse-Extras/jemalloc/blob/e6891d9746143bf2cf617493d880ba5a0b9a3efd/COPYING) |
| krb5 | [MIT](https://github.com/ClickHouse-Extras/krb5/blob/5149dea4e2be0f67707383d2682b897c14631374/src/lib/gssapi/LICENSE) |
| libc-headers | [LGPL](https://github.com/ClickHouse-Extras/libc-headers/blob/a720b7105a610acbd7427eea475a5b6810c151eb/LICENSE) |
| libcpuid | [BSD 2-clause](https://github.com/ClickHouse-Extras/libcpuid/blob/8db3b8d2d32d22437f063ce692a1b9bb15e42d18/COPYING) |
| libcxx | [Apache](https://github.com/ClickHouse-Extras/libcxx/blob/2fa892f69acbaa40f8a18c6484854a6183a34482/LICENSE.TXT) |
| libcxxabi | [Apache](https://github.com/ClickHouse-Extras/libcxxabi/blob/df8f1e727dbc9e2bedf2282096fa189dc3fe0076/LICENSE.TXT) |
| libdivide | [zLib](https://github.com/ClickHouse/ClickHouse/blob/master/contrib/libdivide/LICENSE.txt) |
| libfarmhash | [MIT](https://github.com/ClickHouse/ClickHouse/blob/master/contrib/libfarmhash/COPYING) |
| libgsasl | [LGPL](https://github.com/ClickHouse-Extras/libgsasl/blob/383ee28e82f69fa16ed43b48bd9c8ee5b313ab84/LICENSE) |
| libhdfs3 | [Apache](https://github.com/ClickHouse-Extras/libhdfs3/blob/095b9d48b400abb72d967cb0539af13b1e3d90cf/LICENSE.txt) |
| libmetrohash | [Apache](https://github.com/ClickHouse/ClickHouse/blob/master/contrib/libmetrohash/LICENSE) |
| libpq | [Unknown](https://github.com/ClickHouse-Extras/libpq/blob/e071ea570f8985aa00e34f5b9d50a3cfe666327e/COPYRIGHT) |
| libpqxx | [BSD 3-clause](https://github.com/ClickHouse-Extras/libpqxx/blob/357608d11b7a1961c3fb7db2ef9a5dbb2e87da77/COPYING) |
| librdkafka | [MIT](https://github.com/ClickHouse-Extras/librdkafka/blob/b8554f1682062c85ba519eb54ef2f90e02b812cb/LICENSE.murmur2) |
| libunwind | [Apache](https://github.com/ClickHouse-Extras/libunwind/blob/6b816d2fba3991f8fd6aaec17d92f68947eab667/LICENSE.TXT) |
| libuv | [BSD](https://github.com/ClickHouse-Extras/libuv/blob/e2e9b7e9f978ce8a1367b5fe781d97d1ce9f94ab/LICENSE) |
| llvm | [Apache](https://github.com/ClickHouse-Extras/llvm/blob/e5751459412bce1391fb7a2e9bbc01e131bf72f1/llvm/LICENSE.TXT) |
| lz4 | [BSD](https://github.com/lz4/lz4/blob/f39b79fb02962a1cd880bbdecb6dffba4f754a11/LICENSE) |
| mariadb-connector-c | [LGPL](https://github.com/ClickHouse-Extras/mariadb-connector-c/blob/5f4034a3a6376416504f17186c55fe401c6d8e5e/COPYING.LIB) |
| miniselect | [Boost](https://github.com/danlark1/miniselect/blob/be0af6bd0b6eb044d1acc4f754b229972d99903a/LICENSE_1_0.txt) |
| msgpack-c | [Boost](https://github.com/msgpack/msgpack-c/blob/46684265d50b5d1b062d4c5c428ba08462844b1d/LICENSE_1_0.txt) |
| murmurhash | [Public Domain](https://github.com/ClickHouse/ClickHouse/blob/master/contrib/murmurhash/LICENSE) |
| NuRaft | [Apache](https://github.com/ClickHouse-Extras/NuRaft/blob/7ecb16844af6a9c283ad432d85ecc2e7d1544676/LICENSE) |
| openldap | [Unknown](https://github.com/ClickHouse-Extras/openldap/blob/0208811b6043ca06fda8631a5e473df1ec515ccb/LICENSE) |
| orc | [Apache](https://github.com/ClickHouse-Extras/orc/blob/0a936f6bbdb9303308973073f8623b5a8d82eae1/LICENSE) |
| poco | [Boost](https://github.com/ClickHouse-Extras/poco/blob/7351c4691b5d401f59e3959adfc5b4fa263b32da/LICENSE) |
| protobuf | [BSD 3-clause](https://github.com/ClickHouse-Extras/protobuf/blob/75601841d172c73ae6bf4ce8121f42b875cdbabd/LICENSE) |
| rapidjson | [MIT](https://github.com/ClickHouse-Extras/rapidjson/blob/c4ef90ccdbc21d5d5a628d08316bfd301e32d6fa/bin/jsonschema/LICENSE) |
| re2 | [BSD 3-clause](https://github.com/google/re2/blob/13ebb377c6ad763ca61d12dd6f88b1126bd0b911/LICENSE) |
| replxx | [BSD 3-clause](https://github.com/ClickHouse-Extras/replxx/blob/c81be6c68b146f15f2096b7ef80e3f21fe27004c/LICENSE.md) |
| rocksdb | [BSD 3-clause](https://github.com/ClickHouse-Extras/rocksdb/blob/b6480c69bf3ab6e298e0d019a07fd4f69029b26a/LICENSE.leveldb) |
| s2geometry | [Apache](https://github.com/ClickHouse-Extras/s2geometry/blob/20ea540d81f4575a3fc0aea585aac611bcd03ede/LICENSE) |
| sentry-native | [MIT](https://github.com/ClickHouse-Extras/sentry-native/blob/94644e92f0a3ff14bd35ed902a8622a2d15f7be4/LICENSE) |
| simdjson | [Apache](https://github.com/simdjson/simdjson/blob/8df32cea3359cb30120795da6020b3b73da01d38/LICENSE) |
| snappy | [Public Domain](https://github.com/google/snappy/blob/3f194acb57e0487531c96b97af61dcbd025a78a3/COPYING) |
| sparsehash-c11 | [BSD 3-clause](https://github.com/sparsehash/sparsehash-c11/blob/cf0bffaa456f23bc4174462a789b90f8b6f5f42f/LICENSE) |
| stats | [Apache](https://github.com/kthohr/stats/blob/b6dd459c10a88c7ea04693c007e9e35820c5d9ad/LICENSE) |
| thrift | [Apache](https://github.com/apache/thrift/blob/010ccf0a0c7023fea0f6bf4e4078ebdff7e61982/LICENSE) |
| unixodbc | [LGPL](https://github.com/ClickHouse-Extras/UnixODBC/blob/b0ad30f7f6289c12b76f04bfb9d466374bb32168/COPYING) |
| xz | [Public Domain](https://github.com/xz-mirror/xz/blob/869b9d1b4edd6df07f819d360d306251f8147353/COPYING) |
| zlib-ng | [zLib](https://github.com/ClickHouse-Extras/zlib-ng/blob/6a5e93b9007782115f7f7e5235dedc81c4f1facb/LICENSE.md) |
| zstd | [BSD](https://github.com/facebook/zstd/blob/a488ba114ec17ea1054b9057c26a046fc122b3b6/LICENSE) |

The list of third-party libraries can be obtained by the following query:

``` sql
SELECT library_name, license_type, license_path FROM system.licenses ORDER BY library_name COLLATE 'en';
```

[Example](https://gh-api.clickhouse.com/play?user=play#U0VMRUNUIGxpYnJhcnlfbmFtZSwgbGljZW5zZV90eXBlLCBsaWNlbnNlX3BhdGggRlJPTSBzeXN0ZW0ubGljZW5zZXMgT1JERVIgQlkgbGlicmFyeV9uYW1lIENPTExBVEUgJ2VuJw==)

## Guidelines for adding new third-party libraries and maintaining custom changes in them {#adding-third-party-libraries}

1. All external third-party code should reside in the dedicated directories under `contrib` directory of ClickHouse repo. Prefer Git submodules, when available.
2. Fork/mirror the official repo in [Clickhouse-extras](https://github.com/ClickHouse-Extras). Prefer official GitHub repos, when available.
3. Branch from the branch you want to integrate, e.g., `master` -> `clickhouse/master`, or `release/vX.Y.Z` -> `clickhouse/release/vX.Y.Z`.
4. All forks in [Clickhouse-extras](https://github.com/ClickHouse-Extras) can be automatically synchronized with upstreams. `clickhouse/...` branches will remain unaffected, since virtually nobody is going to use that naming pattern in their upstream repos.
5. Add submodules under `contrib` of ClickHouse repo that refer the above forks/mirrors. Set the submodules to track the corresponding `clickhouse/...` branches.
6. Every time the custom changes have to be made in the library code, a dedicated branch should be created, like `clickhouse/my-fix`. Then this branch should be merged into the branch, that is tracked by the submodule, e.g., `clickhouse/master` or `clickhouse/release/vX.Y.Z`.
7. No code should be pushed in any branch of the forks in [Clickhouse-extras](https://github.com/ClickHouse-Extras), whose names do not follow `clickhouse/...` pattern.
8. Always write the custom changes with the official repo in mind. Once the PR is merged from (a feature/fix branch in) your personal fork into the fork in [Clickhouse-extras](https://github.com/ClickHouse-Extras), and the submodule is bumped in ClickHouse repo, consider opening another PR from (a feature/fix branch in) the fork in [Clickhouse-extras](https://github.com/ClickHouse-Extras) to the official repo of the library. This will make sure, that 1) the contribution has more than a single use case and importance, 2) others will also benefit from it, 3) the change will not remain a maintenance burden solely on ClickHouse developers.
9. When a submodule needs to start using a newer code from the original branch (e.g., `master`), and since the custom changes might be merged in the branch it is tracking (e.g., `clickhouse/master`) and so it may diverge from its original counterpart (i.e., `master`), a careful merge should be carried out first, i.e., `master` -> `clickhouse/master`, and only then the submodule can be bumped in ClickHouse.