Python/FastAPI Developer — Voice Bot Telephony & Speech Integration (Fintech)
Budget: ₹750 – ₹1,250 INR
We're building AffirmoBot, a voice-automation product that helps Indian banks confirm suspicious transactions with
customers via automated phone calls. The proof-of-concept is built and working (Python/FastAPI backend, tested API,
live demo deployment). We need an experienced backend engineer to take it from prototype to production-ready for a
bank pilot.
WHAT YOU'LL BE DOING
1. Outbound telephony integration
Replace our simulated call flow with real outbound calling via Exotel or Tata Tele Smartflo (India-based telephony
providers). The bot must dial a customer, run an authentication + confirmation flow, and handle call-status outcomes
(answered, busy, switched off, unreachable).
2. Speech recognition integration
Integrate Sarvam AI (or equivalent) for real Hindi/Hinglish speech-to-text and text-to-speech, replacing our current
rule-based DTMF/keyword matching.
3. Production database
Move our in-memory session and audit-log storage to PostgreSQL, with proper schema design for call records,
transcripts, and audit trails that must be retained for 5+ years (regulatory requirement).
4. Hardening for a bank security review
Review and improve our existing API-key auth, HMAC-signed callbacks, and input validation. We will have a security
review before going live with a real bank, so code quality and clear documentation matter.
5. Notifications
Wire up our existing SMS (Exotel) and Email (SMTP) notification module into the live call flow for every call outcome.
WHAT WE ALREADY HAVE (so you're not starting from zero)
• Working FastAPI backend with a deterministic state machine (auth -> capture -> confirm/deny -> done)
• A tested, secured API (API-key auth, Pydantic validation, HMAC-signed callbacks) deployed and live
• An automated test suite (21 checks) you'll extend as you add features
• A browser dashboard for simulating and monitoring calls
• Full technical documentation (architecture, API spec, OpenAPI file)
• A mock bank API for integration testing
WHO WE'RE LOOKING FOR
• Strong Python skills, specifically FastAPI or a similar async framework
• Prior experience integrating a telephony/VoIP API (Twilio, Exotel, Plivo, Vonage, or similar) — this is the most
important specific skill
• Comfortable with PostgreSQL schema design
• Bonus: experience with speech-to-text APIs, or fintech/banking-adjacent projects
• Bonus: based in India or familiar with Indian telecom regulations (DLT, TRAI)
• Can work independently and communicate clearly — you'll be the only engineer on this for now, working directly with
the founder
HOW WE'LL WORK TOGETHER
• This is a fixed-scope contract to start (4-6 weeks), with potential for an ongoing arrangement if it goes well
• Daily or every-other-day async updates (Slack/WhatsApp), one weekly call
• All code reviewed via GitHub pull requests
• Payment via milestones (see Milestones section below)
customers via automated phone calls. The proof-of-concept is built and working (Python/FastAPI backend, tested API,
live demo deployment). We need an experienced backend engineer to take it from prototype to production-ready for a
bank pilot.
WHAT YOU'LL BE DOING
1. Outbound telephony integration
Replace our simulated call flow with real outbound calling via Exotel or Tata Tele Smartflo (India-based telephony
providers). The bot must dial a customer, run an authentication + confirmation flow, and handle call-status outcomes
(answered, busy, switched off, unreachable).
2. Speech recognition integration
Integrate Sarvam AI (or equivalent) for real Hindi/Hinglish speech-to-text and text-to-speech, replacing our current
rule-based DTMF/keyword matching.
3. Production database
Move our in-memory session and audit-log storage to PostgreSQL, with proper schema design for call records,
transcripts, and audit trails that must be retained for 5+ years (regulatory requirement).
4. Hardening for a bank security review
Review and improve our existing API-key auth, HMAC-signed callbacks, and input validation. We will have a security
review before going live with a real bank, so code quality and clear documentation matter.
5. Notifications
Wire up our existing SMS (Exotel) and Email (SMTP) notification module into the live call flow for every call outcome.
WHAT WE ALREADY HAVE (so you're not starting from zero)
• Working FastAPI backend with a deterministic state machine (auth -> capture -> confirm/deny -> done)
• A tested, secured API (API-key auth, Pydantic validation, HMAC-signed callbacks) deployed and live
• An automated test suite (21 checks) you'll extend as you add features
• A browser dashboard for simulating and monitoring calls
• Full technical documentation (architecture, API spec, OpenAPI file)
• A mock bank API for integration testing
WHO WE'RE LOOKING FOR
• Strong Python skills, specifically FastAPI or a similar async framework
• Prior experience integrating a telephony/VoIP API (Twilio, Exotel, Plivo, Vonage, or similar) — this is the most
important specific skill
• Comfortable with PostgreSQL schema design
• Bonus: experience with speech-to-text APIs, or fintech/banking-adjacent projects
• Bonus: based in India or familiar with Indian telecom regulations (DLT, TRAI)
• Can work independently and communicate clearly — you'll be the only engineer on this for now, working directly with
the founder
HOW WE'LL WORK TOGETHER
• This is a fixed-scope contract to start (4-6 weeks), with potential for an ongoing arrangement if it goes well
• Daily or every-other-day async updates (Slack/WhatsApp), one weekly call
• All code reviewed via GitHub pull requests
• Payment via milestones (see Milestones section below)