40–70% off your Claude bill.

One line in Claude Code settings. That's it.

Prefex is a local proxy built for Claude Code and the Anthropic API. Intelligent optimization that works invisibly — your workflow doesn't change.

$ curl -fsSL https://prefex.vercel.app/install.sh -o install.sh
$ less install.sh review
$ bash install.sh
$ prefex preview preview changes

macOS, Linux & Windows · ~20MB binary · zero dependencies
Customize: PREFEX_BIND=0.0.0.0 PREFEX_PORT=9019 bash install.sh

40–70% cost reduction
8–12ms added overhead
0 code changes

Install

One command. Then change one setting in your existing API client.

1.
Download and review the install script
Downloads the macOS binary, starts Prefex, and connects Claude Code automatically. Run prefex preview first to see exactly what would change.
$ curl -fsSL https://prefex.vercel.app/install.sh -o install.sh && less install.sh
$ bash install.sh
Custom bind/port: PREFEX_BIND=0.0.0.0 PREFEX_PORT=9019 bash install.sh
2.
Open the dashboard
Prefex is running on :8019. The installer connects Claude Code for you — restart Claude Code to activate.
$ open http://localhost:8019/dashboard

~20MB standalone binary. Zero dependencies. 12 features across three tiers: smart routing + prompt caching + compression (cost) · session memory + context guard + checkpointing (context) · loop guard + token trap + think cap + lean reasoning (guardrails).

1.
Download and review the install script
Downloads the Linux binary, starts Prefex, and connects Claude Code automatically. Run prefex preview first to see exactly what would change.
$ curl -fsSL https://prefex.vercel.app/install.sh -o install.sh && less install.sh
$ bash install.sh
Custom bind/port: PREFEX_BIND=0.0.0.0 PREFEX_PORT=9019 bash install.sh
2.
Open the dashboard
Prefex is running on :8019. The installer connects Claude Code for you — restart Claude Code to activate.
$ xdg-open http://localhost:8019/dashboard

~20MB standalone binary. Zero dependencies. 12 features across three tiers: smart routing + prompt caching + compression (cost) · session memory + context guard + checkpointing (context) · loop guard + token trap + think cap + lean reasoning (guardrails).

1.
Download the install script
Review it before running — it's a PowerShell script and you should know what it does.
PS> iwr https://prefex.vercel.app/install.ps1 -OutFile install.ps1
PS> Get-Content install.ps1 | more
2.
Run it
Downloads the binary, starts Prefex, and connects Claude Code. Customize via $env:PREFEX_BIND and $env:PREFEX_PORT before running.
PS> .\install.ps1
3.
Open the dashboard
Prefex is running. The installer connects Claude Code for you — just restart Claude Code.
PS> Start-Process http://localhost:8019/dashboard
To stop: iwr https://prefex.vercel.app/stop.ps1 -OutFile stop.ps1; .\stop.ps1

~20MB standalone binary. Requires PowerShell 5.1+ and Windows 10/11. Windows support is lightly tested — if you run into issues, email k@daytwoai.com.

Works with your tools

Prefex is a local proxy. Anything that lets you set a custom API base URL works out of the box.

ToolHow to connectStatus
Claude Code Set ANTHROPIC_BASE_URL in ~/.claude/settings.json Auto-configured by installer
Continue.dev Set apiBase for each model in ~/.continue/config.json Supported
Cursor Set ANTHROPIC_BASE_URL env var in your shell Supported
VS Code Set ANTHROPIC_BASE_URL in integrated terminal env settings Supported
Windsurf Set ANTHROPIC_BASE_URL env var in your shell Supported
Aider Run with --api-base http://localhost:8019 Supported
Python / Node SDK Pass base_url="http://localhost:8019" to the client Supported
Any HTTP client Replace api.anthropic.com with localhost:8019 Supported

What you actually save

Real numbers from Claude Code usage over a typical 8-hour dev session.

Scenario Without Prefex With Prefex Saving
Claude Code — daily session ~$4.20 ~$1.40 $2.80 / day
Claude Code — heavy refactoring day ~$12.00 ~$4.80 $7.20 / day
Claude agent — 100 runs/day ~$80 ~$30 $50 / day
Claude API — batch processing 10k docs ~$200 ~$90 $110 / run

See it yourself — run the benchmark

5 code-review questions on public code, run twice — cold then warm. Costs ~$0.02–0.05 total.

1.
Download & review the script
Uses the Claude CLI — no API key export needed. Runs 3 rounds: Prefex cold, Prefex warm, direct baseline.
$ curl -fsSL https://prefex.vercel.app/prefex-bench.sh -o prefex-bench.sh && less prefex-bench.sh
2.
Run it (Prefex must be running)
Requires: claude CLI, python3. Backs up settings, runs benchmark, restores on exit.
$ bash prefex-bench.sh
1.
Download & review the script
Uses the Claude CLI — no API key export needed. Same benchmark as the macOS/Linux version.
PS> iwr https://prefex.vercel.app/prefex-bench.ps1 -OutFile prefex-bench.ps1
PS> Get-Content prefex-bench.ps1 | more
2.
Run it (Prefex must be running)
Requires: claude CLI. Backs up settings, runs benchmark, restores on exit.
PS> .\prefex-bench.ps1
Round Requests Total input tokens Cached tokens Actual cost Saved % saved
Round 1 — cold 5 ~37 000 0 ~$0.042 — —
Round 2 — warm 5 ~37 000 ~34 000 ~$0.005 ~$0.037 ~88%

Costs are read from Anthropic's own billing fields in the SSE stream — not computed by Prefex. Corpus: karpathy/nanoGPT@3adf61e (public, deterministic).

Connect your client

Change one value. Everything else stays the same.

Claude Code
# ~/.claude/settings.json
{
  "env": {
    "ANTHROPIC_BASE_URL": "http://localhost:8019"  ← add this
  }
}
Python (Anthropic SDK)
import anthropic

client = anthropic.Anthropic(
    api_key="sk-ant-...",
    base_url="http://localhost:8019",  ← add this
)
Node.js (Anthropic SDK)
import Anthropic from "@anthropic-ai/sdk";

const client = new Anthropic({
  apiKey: "sk-ant-...",
  baseURL: "http://localhost:8019",  // ← add this
});
cURL
curl http://localhost:8019/v1/messages \
  -H "x-api-key: $ANTHROPIC_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "content-type: application/json" \
  -d '{"model":"claude-sonnet-4-6","max_tokens":1024,"messages":[{"role":"user","content":"Hello"}]}'

Your prompts never leave your machine.

Prefex runs entirely on localhost. There is no telemetry, no analytics, no external logging service. If any internal component fails — requests pass through to the upstream API unchanged. Prefex never blocks a request because of its own failure.

Verify it yourself with tcpdump: 

# All outbound traffic from Prefex should go only to api.anthropic.com
sudo tcpdump -i any -n 'dst port 443' 2>/dev/null | grep -v api.anthropic.com
Full privacy and data handling details →

Download, review, run. Savings from the first request.

$ curl -fsSL https://prefex.vercel.app/install.sh -o install.sh
$ less install.sh review
$ bash install.sh
$ prefex preview preview changes
github.com/PromptForcePrime/prefex →

Free to use

30-day license, renewable online. No credit card. No call-home. Renew →

Marketplace

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Uninstall / restore

Stop Prefex and point Claude Code back to Anthropic directly.

macOS / Linux — one command:

$ curl -fsSL https://prefex.vercel.app/uninstall.sh | bash

Add --purge to also delete ~/.prefex (logs, cache, config).

Windows (PowerShell):

PS> iwr https://prefex.vercel.app/uninstall.ps1 -OutFile uninstall.ps1; .\uninstall.ps1

Add -purge to also delete %USERPROFILE%\.prefex (logs, cache, config).

Manually restore ~/.claude/settings.json:

Remove or change the ANTHROPIC_BASE_URL entry back to https://api.anthropic.com: 

{
  "env": {
    "ANTHROPIC_BASE_URL": "https://api.anthropic.com"
  }
}

Then restart Claude Code. If you had no settings.json before installing Prefex, you can delete the file entirely.

Full cleanup (remove all Prefex data):

$ curl -fsSL https://prefex.vercel.app/uninstall.sh | bash -s -- --purge

Windows: .\uninstall.ps1 -purge

Stops Prefex, removes the binary, restores settings, and deletes ~/.prefex.