Hi HN! We're excited to introduce "Karl" – a virtual friend you can text to share what's on your mind.<p>We created Karl because we found it incredibly helpful to have a sounding board and someone I could talk to anytime, day or night.<p>Karl isn't meant to replace real friendships but rather to act as a mediator and an additional point of contact. He remembers important details you share and can connect the dots between past events and current decisions.<p>Anyone can message Karl by texting +1 (844) 619-7958
. There’s no separate app or website – just text to start a conversation. The first ten messages are free, after which Karl charges 10 per month to continue (and to help cover Karl's dining habits).<p>On the backend, we primarily use 4o (OpenAI) to handle message flow and identify important memories. All the code for LLM calls, context management, and tool use is custom-built, as we found frameworks like Langchain to be too much overhead.<p>Moving forward, we plan to run a fine-tuned 4o-mini model and experiment with other providers. Texting is powered by Twilio (and FYI – getting a non-sandbox phone number is quite a process), and we use Postgres (via Supabase) to store conversations and context. The entire service runs on Render.<p>We’re also working on new features like proactive check-ins and smarter memory handling.<p>Karl is currently in early alpha. We'd love feedback from the HN community at hello@heykarl.xyz. Please say hi, and we hope you have some great conversations!