diff --git a/.builds/c-enabled.yml b/.builds/c-enabled.yml
index 6f03b0564c3a1103959b6566f59e667367981034..d47ebfcbec5f54f24b4fc4e542cce33797a8792f 100644
--- a/.builds/c-enabled.yml
+++ b/.builds/c-enabled.yml
@@ -77,9 +77,26 @@   - install_tarantool: |
       curl -L https://tarantool.io/release/3/installer.sh | sudo bash
       sudo apt-get install -y tarantool tarantool-dev tt
   - install_just: |
+      JUST_VERSION=1.51.0
+      JUST_TARBALL="just-${JUST_VERSION}-x86_64-unknown-linux-musl.tar.gz"
+      JUST_KEY="just/$JUST_TARBALL"
+      JUST_URI="s3://$S3_BUCKET/$JUST_KEY"
       mkdir -p ~/.local/bin
-      curl --proto '=https' --tlsv1.2 -sSf https://just.systems/install.sh \
-        | bash -s -- --to ~/.local/bin
+      if aws --endpoint-url="$AWS_ENDPOINT_URL" s3api head-object \
+           --bucket "$S3_BUCKET" --key "$JUST_KEY" >/dev/null 2>&1; then
+        echo "Cache HIT — pulling just from S3"
+        aws --endpoint-url="$AWS_ENDPOINT_URL" s3 cp "$JUST_URI" - \
+          | tar -xz -C ~/.local/bin just
+      else
+        echo "Cache MISS — downloading from github and caching"
+        curl -sSL --retry 3 --retry-delay 5 --max-time 60 \
+          "https://github.com/casey/just/releases/download/${JUST_VERSION}/${JUST_TARBALL}" \
+          -o "/tmp/$JUST_TARBALL"
+        tar -xz -C ~/.local/bin -f "/tmp/$JUST_TARBALL" just
+        aws --endpoint-url="$AWS_ENDPOINT_URL" s3 cp "/tmp/$JUST_TARBALL" "$JUST_URI"
+        rm "/tmp/$JUST_TARBALL"
+      fi
+      just --version
   - install_luatest: |
       cd tarantool-protobuf
       tt rocks install luatest
diff --git a/.builds/conformance.yml b/.builds/conformance.yml
index 983c60d42909bce1b92fae2bd9b5ca24f55eed87..78b42c2a78f028033726da6ebdcd09c964d3f493 100644
--- a/.builds/conformance.yml
+++ b/.builds/conformance.yml
@@ -91,9 +91,26 @@   - install_tarantool: |
       curl -L https://tarantool.io/release/3/installer.sh | sudo bash
       sudo apt-get install -y tarantool tarantool-dev tt
   - install_just: |
+      JUST_VERSION=1.51.0
+      JUST_TARBALL="just-${JUST_VERSION}-x86_64-unknown-linux-musl.tar.gz"
+      JUST_KEY="just/$JUST_TARBALL"
+      JUST_URI="s3://$S3_BUCKET/$JUST_KEY"
       mkdir -p ~/.local/bin
-      curl --proto '=https' --tlsv1.2 -sSf https://just.systems/install.sh \
-        | bash -s -- --to ~/.local/bin
+      if aws --endpoint-url="$AWS_ENDPOINT_URL" s3api head-object \
+           --bucket "$S3_BUCKET" --key "$JUST_KEY" >/dev/null 2>&1; then
+        echo "Cache HIT — pulling just from S3"
+        aws --endpoint-url="$AWS_ENDPOINT_URL" s3 cp "$JUST_URI" - \
+          | tar -xz -C ~/.local/bin just
+      else
+        echo "Cache MISS — downloading from github and caching"
+        curl -sSL --retry 3 --retry-delay 5 --max-time 60 \
+          "https://github.com/casey/just/releases/download/${JUST_VERSION}/${JUST_TARBALL}" \
+          -o "/tmp/$JUST_TARBALL"
+        tar -xz -C ~/.local/bin -f "/tmp/$JUST_TARBALL" just
+        aws --endpoint-url="$AWS_ENDPOINT_URL" s3 cp "/tmp/$JUST_TARBALL" "$JUST_URI"
+        rm "/tmp/$JUST_TARBALL"
+      fi
+      just --version
   - install_luatest: |
       cd tarantool-protobuf
       tt rocks install luatest
diff --git a/.builds/pure-lua.yml b/.builds/pure-lua.yml
index 1413d9146091cc3a3c4b5455f356fe9bf742f1fd..b03177f8a44e207c166293a9ea823a60f97ae5df 100644
--- a/.builds/pure-lua.yml
+++ b/.builds/pure-lua.yml
@@ -76,9 +76,26 @@   - install_tarantool: |
       curl -L https://tarantool.io/release/3/installer.sh | sudo bash
       sudo apt-get install -y tarantool tarantool-dev tt
   - install_just: |
+      JUST_VERSION=1.51.0
+      JUST_TARBALL="just-${JUST_VERSION}-x86_64-unknown-linux-musl.tar.gz"
+      JUST_KEY="just/$JUST_TARBALL"
+      JUST_URI="s3://$S3_BUCKET/$JUST_KEY"
       mkdir -p ~/.local/bin
-      curl --proto '=https' --tlsv1.2 -sSf https://just.systems/install.sh \
-        | bash -s -- --to ~/.local/bin
+      if aws --endpoint-url="$AWS_ENDPOINT_URL" s3api head-object \
+           --bucket "$S3_BUCKET" --key "$JUST_KEY" >/dev/null 2>&1; then
+        echo "Cache HIT — pulling just from S3"
+        aws --endpoint-url="$AWS_ENDPOINT_URL" s3 cp "$JUST_URI" - \
+          | tar -xz -C ~/.local/bin just
+      else
+        echo "Cache MISS — downloading from github and caching"
+        curl -sSL --retry 3 --retry-delay 5 --max-time 60 \
+          "https://github.com/casey/just/releases/download/${JUST_VERSION}/${JUST_TARBALL}" \
+          -o "/tmp/$JUST_TARBALL"
+        tar -xz -C ~/.local/bin -f "/tmp/$JUST_TARBALL" just
+        aws --endpoint-url="$AWS_ENDPOINT_URL" s3 cp "/tmp/$JUST_TARBALL" "$JUST_URI"
+        rm "/tmp/$JUST_TARBALL"
+      fi
+      just --version
   - install_luatest: |
       cd tarantool-protobuf
       tt rocks install luatest