Developers

Size battery systems against certified tariffs — from code, or from an agent.

The same tools, the same sandbox, whether you call the API by hand or let Claude Code call it for you. No key needed to start.

Connect in three lines → Open the Playground API Reference

Playground

Browse the certified tariff catalog in the browser and get real JSON back. Look before you connect. The other endpoints need a key.

Open the Playground
auth: none · sandbox

Build with AI

The WattChop MCP server: ten tools an agent calls while writing code, plus the build charters shipped inside it.

Connect the server
auth: none = sandbox · API key = keyed

API Reference

The published OpenAPI spec and the reference articles.

Read the reference
auth: key required for calls
Build with AI

Connect the server

The WattChop MCP server provides tools that AI agents can use to size and score battery and PV systems against certified tariffs through the WattChop API, and to read the WattChop developer documentation.

One line in your terminal.

claude mcp add --transport http wattchop https://mcp.wattchop.com/mcp

Keyed: add --header "X-Api-Key: <key>". No key = sandbox.

Building with an AI agent? Connect in three lines — no key needed.

Don’t trust the AI? Fine — read the payloads yourself. The answers are the same either way.

Then follow a build charter

The ten tools

Tariffs

tariff_catalog_search
Find certified tariffs by utility, name, or region.
tariff_get
Read one tariff in full, with the version it is pinned to.

Every tariff you size against comes from the WattChop Library — validated, never raw.

Load

building_types
List the building classifications a load can be built from.
list_samples
List the sample load profiles the sandbox can run against.
synthesize_load
Turn twelve monthly kWh figures into an interval load profile.

Sizing

sizing_run
Start a sweep that searches for the system the math supports.
sizing_score
Score a battery and PV size you specify against a tariff.
sizing_result
Fetch a run's result from the handle it returned.

Docs

docs_search
Search the WattChop developer documentation.

Session

wallet_status
Reports which mode your session is in (sandbox or keyed).

How long a run takes depends on the load profile you hand it. A score against a clean sample profile sits at the light end; a sweep across a dense or irregular year sits at the heavy end. Sizing runs always hand back a run handle you poll with sizing_result, so a long run never looks like a stalled one.

Sandbox versus keyed

What each one reaches

Sandbox

  • Certified public tariffs
  • Sample load profiles
  • Synthesized loads from monthly kWh
  • Rate-limited exploration

Free isn't anonymous — every endpoint needs a credential. Sandbox works because the MCP server holds one for you.

Keyed

  • Your own interval data
  • Private tariffs
  • Volume

Every result says which mode it came from.

Ready for a key →
API Reference

The published spec

https://app.wattchop.com/api/v1/openapi.json

Open the spec Open the Playground

Building with an AI agent? Connect in three lines — no key needed. Start there.

MCP server — checking
What a result carries

Attribution, both figures, the version

A WattChop sizing result: the attribution block, both savings figures — without optimization, then with — and the certified tariff version the run was priced against. Gold marks the size the optimizer landed on.

Gold marks the one place the algorithm decided something — the size it landed on.

Every result carries “Powered by WattChop.” Every sizing result shows both savings figures and the tariff version it ran against.

Questions

The four we actually get

Am I competing with this?

No — structurally. WattChop returns schedules, not commands: the intelligence layer, never the execution layer. Your EMS, your app, your brand, your customer. Two things survive into your product — “Powered by WattChop” and both savings figures. Everything else is yours.

What is WattChop?

The tariff intelligence layer. Send a site's interval data, or twelve monthly bills, and get back the answer modeled against its real tariff — the optimal size, with the savings math behind it. The map your product's autopilot needs.

Why do I need it?

The algorithm was the fun part. The tariff data is the job — 2,900+ utility tariffs, riders, ratchets, seasonal windows, kept current. It goes stale silently and corrupts every number downstream, and nobody budgets for it. We did.

Will my competitors use it?

Yes, eventually. That's the argument for being first, not for staying away. The tariff-naive product is the one that loses the bake-off.