PromptUnit

PromptUnit is an API proxy for teams trying to reduce model spending without replacing their coding tool or application. Its published setup guides cover Claude Code, Cursor, Cline, Windsurf and Codex CLI. Requests pass through PromptUnit's servers, where the company says its Inferio routing engine chooses a lower-cost model when that model meets a configured quality threshold.

Put routing behind a measurable trial

The technical documentation describes a fourteen-day observation period. During that period, routing runs in shadow mode: the dashboard records projected decisions without changing which model handles the request. That offers a useful way to inspect proposed substitutions before enabling them on production traffic.

The documentation describes passthrough to the requested model when no cheaper model qualifies. It also lists compression, request caching and output-format checks as conditional processing stages. These are vendor descriptions of the system, not independent proof that a cheaper response will preserve correctness. Test repository changes and application outputs against your own acceptance criteria, especially where a valid response format can still contain an incorrect answer.

Inspect the model that handled each call

PromptUnit's response headers distinguish the requested model from the model that actually ran. Other documented headers report cost, latency, routing status and the savings estimate. The optional feature tag separates spending for product functions such as support or summarization.

The proxy publishes OpenAI-compatible chat-completions and Anthropic messages endpoints with streaming support. Provider names and compatibility claims do not establish an affiliation with those providers, or guarantee every client feature will work. Use the client-specific setup guides and try tool calls, long sessions and error recovery before changing a team's default configuration.

Requests and code traverse the proxy. PromptUnit says it does not retain prompt, code or response content; its logging modes retain different amounts of metadata. Review that routing and retention arrangement against your organization's rules before sending confidential repositories.

Reconcile billing before connecting broadly

The homepage advertises the first $5 of savings free, followed by a fee equal to 20% of ongoing savings. It says the tool returns an add-card error when the free allowance ends. The technical documentation also lists monthly billing and a $1 setup fee credited to the first invoice, which conflicts with the homepage's no-setup-fee statement. Confirm the applicable offer before purchasing.

Savings mean the difference between the requested model's estimated cost and the routed request's cost. A percentage fee depends on that comparison, so inspect the call log rather than treating the headline savings rate as a promised reduction. Check spend limits and fallback behavior as part of the trial, then expand only after the outputs and billing match expectations.