Technical Co-Founder / CTO

Company Description

BLACKLINE is an exclusive private membership platform designed to provide an exceptional experience in aesthetics, wellness, fitness, and personal care across London. We pride ourselves on a meticulously curated network of top-tier operators to meet members' high standards. With a focus on personalized attention, BLACKLINE offers a seamless and bespoke experience. Membership is granted selectively, catering to individuals who value excellence and exclusivity.

Increase your chances of an interview by reading the following overview of this role before making an application.

Technical Co-Founder / CTO — BLACKLINE

Overview

BLACKLINE is a private, invite-only membership across London focused on health, beauty, and personal care.

We are building a concierge layer powered by AI — designed to handle booking, coordination, and member preferences across messaging and voice, with the standard and discretion expected of a private members’ network.

This is not a typical startup role.

We are building infrastructure for experience, not a product for scale.

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What You’ll Build

You will architect and ship the BLACKLINE Concierge Agent, operating across:

1. WhatsApp (Primary Interface)

* Natural conversation handling (LLM-driven)

* Booking coordination with providers

* Memory of member preferences

* Context-aware responses (time, location, history)

2. Voice (Phone Concierge)

* Real-time conversational agent

* Natural, human-like voice (e.g. ElevenLabs or equivalent)

* Call handling (inbound + outbound)

* Seamless escalation to human when required

3. Backend Intelligence Layer

* User profiles + preference memory

* Provider availability + scheduling logic

* Workflow orchestration (requests → bookings → confirmations)

* CRM integration

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Core Responsibilities

* Design and build the end-to-end AI concierge system

* Select and integrate LLMs, voice models, and orchestration frameworks

* Build WhatsApp automation (e.g. via Twilio, Meta APIs, or equivalent)

* Implement real-time voice pipeline (speech-to-text → reasoning → text-to-speech)

* Ensure low latency and high reliability

* Maintain strict data privacy and security standards

* Define architecture that scales without degrading experience

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Technical Requirements

You should have strong hands-on experience in:

AI / LLM Systems

* Prompt engineering + agent design

* Tool use / function calling

* Memory systems (vector DBs, session memory)

* Multi-step workflow orchestration

Voice Systems

* Real-time speech pipelines (STT / TTS)

* Latency optimisation for conversational flow

* Experience with providers like ElevenLabs or similar

Messaging Infrastructure

* WhatsApp API integrations

* Event-driven systems

* Webhooks and async processing

Backend Engineering

* Node.js / Python (preferred)

* API design

* Database design (relational + vector)

* Cloud infrastructure (AWS / GCP)

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What We Care About (More Than Stack)

* You ship fast — not just design systems

* You understand user experience in conversation, not just code

* You can balance automation vs human touch

* You care about detail, tone, and discretion

This is not:

* a chatbot

* a support tool

* a generic AI assistant

It must feel like:

a private concierge that already knows the member

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Nice to Have

* Experience building AI agents in production

* Experience with booking / scheduling systems

* Familiarity with CRM tools (HubSpot, custom pipelines)

* Background in high-end consumer or service experiences

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Stage & Commitment

* Early-stage / pre-scale

* Building MVP → live concierge → refined system

* Equity-based co-founder role

* London-based preferred (not mandatory)

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What Success Looks Like

* A member can message or call BLACKLINE

* Make a request in natural language

* Have it handled seamlessly end-to-end

No friction.

No repetition.

No drop in standard.

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Why This Matters

Most AI products optimise for efficiency. xwzovoh

We’re optimising for:

* trust

* consistency

* experience

If you get this right, you’re not building a feature —

• you’re building the operating system of the brand.