# Compresso common questions

## What is Compresso?

A macOS app that cuts what Claude Code and Codex cost you to run. It sits
between your agent and the provider as a local compression layer, shrinking the
context each request carries before that request is billed. Same agent, same
answers, fewer tokens on the invoice.

## What does it actually do to my requests?

Two things, both on your Mac. A cache-aligning stage keeps the start of your
request byte-identical from turn to turn, so the provider's cache discount
survives. Then a router detects what each piece of content is, JSON, source
code, logs, diffs, search results, and hands it to the compressor built for
that kind. Only the newest content is touched: your system prompt, your tool
definitions and every earlier turn are left exactly as they are, and no message
is ever dropped from history. [How it works](/how-it-works) has the full
pipeline.

## What do I get in the app?

Two screens. **Overview** shows what you saved, tokens removed before the
request left your Mac counted separately from the ones your provider discounted
for you, split by agent and by day over seven or thirty. **Agents** connects
and disconnects each agent in one click, with a pause switch for when you want
Compresso out of the way. [Features](/features) covers both.

## Does Compresso read my API keys or credentials?

Compresso never collects them. The `Authorization` header is copied through
byte for byte, never stored, and never logged, and no credential ever reaches
our servers. It is read in one place, on your Mac, in memory, for one purpose:
working out which Claude or ChatGPT plan you are on, so the app can offer you
the tier that matches. Your Claude token is used to ask Anthropic's own account
endpoint about your plan over the session your agent is already signed in
with, at most once a day for each of those sessions, plus one check you can force
with the app's Refresh button and no more than once a minute; your ChatGPT plan
is already inside the token, so the app reads it locally with no request at all.
The plan we work out stays on your machine, with one exception: when you open
checkout, the app tells us which tier to bill you for, because that is what a
purchase is. That happens when the
checkout page opens rather than when you pay, and no other request carries it.
Compresso never touches the credential files your tools keep on disk. The narrow read is structurally bounded: the request type used for
routing and counting still has no field that could hold a credential, and the
one function that reads the token is private to the app's core, so the
background helper cannot call it.

## Do my prompts or code pass through Compresso's servers?

No. Optimization runs entirely on your Mac. Requests go from your agent,
through a local loopback port, directly to Anthropic or OpenAI. Compresso's
servers never see a prompt, a file, or a line of your code.

## What data leaves my Mac?

Aggregate counters only: tokens before, tokens after, tokens saved, request
counts, per agent, per day, plus your account email and device registration.
No prompts, no code, no file names, no payloads. The [privacy policy](/privacy)
lists every field.

## What happens if Compresso breaks mid-session?

Your tools keep working. If the optimizer is down, still starting, or anything
else goes wrong, requests pass straight through to the provider unmodified,
in under a second, with no dead port. Quitting the app doesn't break your
agents either; a background helper keeps the port answering.

## Does it work with Claude Pro/Max or ChatGPT plans?

Yes. Subscription traffic has no per-token price, so Compresso reports **room,
not dollars**, headroom against your plan's limits instead of an invented
dollar figure. Token savings are measured the same way regardless of how you
pay.

## Can I trust the savings numbers?

The token count is measured, not modelled: context that never left your machine
was never billed, by anyone, at any rate. Dollar figures are estimates, marked
with ≈, priced against your real cache mix, never a flat uncached rate. The
two are never summed.

## What does Compresso change on my machine?

It sets the base URL in your Claude Code and Codex config files, the apps' own
settings, nothing else. Every write gets a timestamped backup first. It never
touches your shell profile, your `PATH`, or another app's data.

## How many Macs can I use?

Up to 2 Macs per account.

## How much does Compresso cost?

Three tiers, each matched to a provider plan: **Pro** for Claude Pro or ChatGPT
Plus, **Max 5x** for Claude Max 5x or ChatGPT Pro, and **Max 20x** for Claude
Max 20x or ChatGPT Pro 20x. Every tier includes everything — up to 2 Macs and a
7-day free trial — and every tier is 50% off for its first 3 months, billed
monthly or yearly. The [pricing page](/pricing) has the current figures.

## What happens when my trial or subscription ends?

Compresso quietly steps out of the way: requests pass through unoptimized, your
tools keep working, and nothing breaks. An expired subscription is a
passthrough, never a broken toolchain. Subscribe from inside the app to turn
optimization back on.

## Which agents are supported?

Claude Code and Codex today. The intercept is agent-agnostic at the protocol
level; more agents are a product decision, not a rewrite.

## Is the engine open source?

Yes, Compresso runs the open-source `headroom` engine (Apache-2.0), fetched at
first launch and run entirely on your machine. Downloads are integrity-checked;
a checksum mismatch is a hard failure, never a shrug.