Devatraj Bhattacharjee
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What I do, 1 of 5

Replace what you pay for

If a vendor bill grows with your traffic, I build the in-house version and prove it gives the same answers before you switch.

$115Ka year saved across two replacements

Who it's for: Founders, CTOs and engineering managers with a vendor bill that keeps growing.

The problem

Try it

A small working tool. Change the numbers.

Should you build it in-house?

Put in your vendor bill and a rough build cost. See when building pays for itself.

VendorIn-house
–until it pays for itself
–saved over 3 years
–you'd pay the vendor in 3 years

A rough estimate to start the conversation. My two replacements save about $115,000 a year combined.

Where I've done it

milanSathi

milanSathi

Built milanSathi, an in-house AI-powered astrology engine (kundli + kundli-milan) that replaced a paid third-party astrology API.

  • ~$45,000/year saved
  • 100% parity with the vendor on everything tested
Read the case study

Jeevansathi

Firebase Remote Config, replaced

Built an in-house feature-configuration platform (Spring Boot, Redis, MongoDB) that replaced Firebase Remote Config after it moved to a paid tier.

  • $70,000/year licensing cost eliminated
  • 10M+ requests/day

milanSathi

milanSathi: proof before switching

Proved correctness against the vendor before switching traffic.

  • 284/284 Ashtakoota combinations + 55 real pairs
  • 729/729 Dashakoota cells
  • 81/81 planet positions
  • Vimshottari dasha matched to the minute

Kundli match

Ashtakoota, 8 kootas

Good match

AI conversation starter

You both have the Moon in earth signs. Ask about the last thing they built with their hands.

Illustration with sample scores

milanSathi. Replaced a paid astrology API. Try another match.
Config panelIllustration
home_screen_variantAndroid
  1. app version = 33.5"off"a build with a known bug
  2. app version >= 34.0"v2"new home screen
  3. app version >= 33.0"v1"
  4. no rule matchesapp default

The app gets "v2"

    Config platform. Replaced Firebase Remote Config. Drag the version, then fetch twice.

    How I'd do it for you

    1. Inventory what you really use

      Most teams use a fraction of what they pay for. That fraction is all we rebuild.

    2. Build it in-house

      Same contract, so the rest of your code barely notices.

    3. Prove it matches

      Check it against the vendor on real data before any traffic moves.

    4. Switch safely

      Roll out behind a flag, with automatic fallback to the vendor.

    Need this?

    Tell me what you're working with. I'll tell you honestly whether it's worth doing and roughly what it takes.

    Email me about this