diff --git a/README.md b/README.md
index 51d4191..ee63cbd 100644
--- a/README.md
+++ b/README.md
@@ -545,6 +545,7 @@ The following clients have engaged Trail of Bits for 5 or more security reviews:
 | ---| --: | :-: | --- | :-: |
 | [Ripple Labs XRP Ledger Confidential Transfer](https://ripple.com/) | Apr 2026 | 6 | | [📄✅](reviews/2026-04-ripple-labs-xrp-ledger-confidential-transfer-securityreview.pdf) |
 | [Open Home Foundation SecureTar v3](https://www.openhomefoundation.org/) | Mar 2026 | 1 | | [📄✅](reviews/2026-03-open-home-foundation-securetar-v3-securityreview.pdf) |
+| [Obsidian Sync](https://obsidian.md/) | Dec 2025 | 2 | | [📄✅](reviews/2025.12-obsidiansync-securityreview.pdf) |
 | [NEAR One PedPop+](https://nearone.org/) | May 2025 | 4 | | [📄](reviews/2025-05-near-one-pedpop+-securityreview.pdf) |
 | [NEAR One MPC Chain Signatures](https://docs.near.org/chain-abstraction/chain-signatures) | Mar 2025 | 6 | | [📄](reviews/2025-03-near-one-mpc-chain-signatures-securityreview.pdf) |
 | [NEAR One Robust ECDSA](https://docs.near.org/chain-abstraction/chain-signatures) | Feb 2026 | 6.4 | | [📄✅](reviews/2026-02-near-one-robust-ecdsa-securityreview.pdf) |
diff --git a/reviews/2025.12-obsidiansync-securityreview.pdf b/reviews/2025.12-obsidiansync-securityreview.pdf
new file mode 100644
index 0000000..cac1504
Binary files /dev/null and b/reviews/2025.12-obsidiansync-securityreview.pdf differ