espeak-ng

git clone https://github.com/espeak-ng/espeak-ng.git
cd espeak-ng
mkdir build && cd build
cmake .. -DBUILD_SHARED_LIBS=OFF -DCMAKE_INSTALL_PREFIX=../install -DUSE_SPEECHPLAYER=FALSE -DUSE_LIBSONIC=FALSE -DUSE_PCAUDIO=FALSE 
cmake --build . --config Release
cmake --install . --config Release

curl -X POST http://127.0.0.1:8080/v1/audio/speech \
  -H "Content-Type: application/json" \
  -d '{"model":"kokoro","input":"Hello, this is a test.","voice":"af_sky","speed":1.0}' \
  --output test.wav