diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
index 324466e..58be68b 100644
--- a/.github/workflows/tests.yaml
+++ b/.github/workflows/tests.yaml
@@ -11,6 +11,72 @@ jobs:
     if: "github.event_name == 'pull_request'"
     uses: "matrix-org/backend-meta/.github/workflows/sign-off.yml@v2"
 
+  js-latest-main:
+    name: Tests (JS only, latest main)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3 # Checkout crypto tests
+      - name: Setup | Node.js 18.x
+        uses: actions/setup-node@v3
+        with:
+          node-version: 18
+          cache: 'yarn'
+          cache-dependency-path: "internal/api/js/js-sdk/yarn.lock"
+      - name: Setup | Go
+        uses: actions/setup-go@v4
+        with:
+          go-version: '1.21'
+      - name: Setup | Rust # TODO: Remove when we have conditional builds
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: stable
+      - name: Check out Rust SDK # TODO: Remove when we have conditional builds
+        run: |
+          ./install_uniffi_bindgen_go.sh
+          mkdir rust-sdk # don't use HTTPS path in rebuild_rust_sdk.sh so we can use the rust-cache before building
+          (wget -O - "https://github.com/matrix-org/matrix-rust-sdk/archive/kegan/complement-crypto.tar.gz" | tar -xz --strip-components=1 -C rust-sdk)
+      - uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: "rust-sdk"
+      - name: Build Rust SDK # TODO: Remove when we have conditional builds
+        run: |
+          ./rebuild_rust_sdk.sh ./rust-sdk
+      - name: "Install Complement Dependencies"
+        run: |
+          sudo apt-get update && sudo apt-get install -y libolm3 libolm-dev
+          go install -v github.com/gotesttools/gotestfmt/v2/cmd/gotestfmt@latest
+      - name: Build JS SDK (branch 'develop')
+        run: |
+          ./rebuild_js_sdk.sh matrix-js-sdk@https://github.com/matrix-org/matrix-js-sdk#develop
+      - name: Pull synapse service v1.94.0 and mitmproxy
+        shell: bash
+        run: |
+          docker pull ghcr.io/matrix-org/synapse-service:v1.94.0
+          docker pull mitmproxy/mitmproxy:10.1.5
+          docker tag ghcr.io/matrix-org/synapse-service:v1.94.0 homeserver:latest
+      - run: |
+          export LIBRARY_PATH="$(pwd)/rust-sdk/target/debug"
+          export LD_LIBRARY_PATH="$(pwd)/rust-sdk/target/debug"
+          set -o pipefail &&
+          go test -v -json -timeout 15m ./tests | gotestfmt
+        shell: bash # required for pipefail to be A Thing. pipefail is required to stop gotestfmt swallowing non-zero exit codes
+        name: Run Complement Crypto Tests
+        env:
+          COMPLEMENT_BASE_IMAGE: homeserver
+          COMPLEMENT_ENABLE_DIRTY_RUNS: 1
+          COMPLEMENT_CRYPTO_WRITE_CONTAINER_LOGS: 1
+          COMPLEMENT_CRYPTO_TEST_CLIENT_MATRIX: jj # only run JS tests (TODO: also runs some rust tests regardless)
+          COMPLEMENT_SHARE_ENV_PREFIX: PASS_
+          PASS_SYNAPSE_COMPLEMENT_DATABASE: sqlite
+          DOCKER_BUILDKIT: 1
+
+      - name: Upload logs
+        uses: actions/upload-artifact@v2
+        if: ${{ always() }} # do this even if the tests fail
+        with:
+          name: Logs - ${{ job.status }}
+          path: |
+            ./tests/logs/*
 
   rust-latest-main:
     name: Tests (Rust only, latest main)
diff --git a/rebuild_js_sdk.sh b/rebuild_js_sdk.sh
index ada99aa..6ea5e31 100755
--- a/rebuild_js_sdk.sh
+++ b/rebuild_js_sdk.sh
@@ -16,6 +16,6 @@ then
     exit 1
 fi
 
-(cd js-sdk && yarn add $1 && yarn install && yarn build)
+(cd ./internal/api/js/js-sdk && yarn add $1 && yarn install && yarn build)
 rm -rf ./internal/api/js/chrome/dist || echo 'no dist directory detected';
-cp -r ./js-sdk/dist/. ./internal/api/js/chrome/dist
+cp -r ./internal/api/js/js-sdk/dist/. ./internal/api/js/chrome/dist