Proxy
Open-source AI proxy cuts agent API costs ~90% with smart routing and anomaly detection.
If you run Claude Code or any agent on Anthropic's new per-token billing, this proxy is the cheapest way to keep your bill inside subscription caps. Setup takes seconds. The multi-credential pool and anomaly detection alone justify it. For OpenAI-only shops, savings are smaller but still real.
- Teams using Claude Code or OpenClaw under Anthropic's June 2026 per-token billing
- Developers deploying multiple AI agents that need per-tenant budget enforcement
- Organizations wanting a local, open-source proxy with anomaly detection to prevent runaway agent costs
- Cost-conscious users of LLM-powered coding tools who want to route simple tasks to cheaper models automatically
- Users who prefer a fully managed cloud SaaS with no self-hosting
- Teams using exclusively GPT-4o or Gemini without Anthropic models (cost-saving potential is lower)
- Non-technical users who are not comfortable with CLI installation or environment variable configuration
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In short
Proxy — Open-source AI proxy cuts agent API costs ~90% with smart routing and anomaly detection. Best for Teams using Claude Code or OpenClaw under Anthropic's June 2026 per-token billing, Developers deploying multiple AI agents that need per-tenant budget enforcement, Organizations wanting a local, open-source proxy with anomaly detection to prevent runaway agent costs. Free to use.
What's new in Proxy
Checked 11 days agoAcross the latest 7 updates: 5 feature updates, 1 pricing change and 1 changelog entry.
v 1.9.39: Live cost ticker shipped with `relayplane watch` subcommand
Live cost ticker end-to-end: terminal UI showing spend, session, model distribution, last 5 requests. Backed by /v1/stats/live endpoint.
v 1.9.38: Claim-nudge auto-initiates device-auth flow at 100 requests
Proxy auto-initiates device-auth flow at 100-request threshold to convert anonymous users to workspace.
v 1.9.36: TokenPool credential quarantine after 2 consecutive 401s
Credentials evicted from rotation after 2 consecutive 401s, ensuring next request uses a known-good token.
v 1.9.34: Budget enforcement correctly respects config.enabled
Fixed budget enforcement to skip session checks when budget is disabled via config.enabled.
v 1.9.33: /v1/estimate now Free-tier
Preflight cost checks via /v1/estimate no longer require Pro subscription; available to free users.
v 1.9.31: Phase B background-activity detection foundation
Background-activity detection added as foundation for upcoming watch CLI Phase B features.
v 1.9.30: Multi-credential pool with fallback chain per tenant
Multi-credential pool allows primary + fallback credentials per tenant; RelayPlane rotates on auth failure.
Viability Score
How likely is Proxy to still be operational in 12 months? Based on 4 signals — momentum (how recently it shipped), wrapper dependency, revenue model, and web presence.
Last calculated: July 2026
How we score →Key Features
- Smart model routing: classifies tasks (simple/agentic/judgment) and assigns cheapest fitting model
- Multi-credential pool: round-robins across Pro, Max, and API keys to avoid rate limits and quota caps
- Quota-aware fail-over: shifts traffic before credential quotas are hit
- Anomaly detection: velocity spikes, token explosions, repetition loops in sliding 100-request window
- Hard budget caps per agent, per tenant, per day (configurable actions: block, downgrade, warn, alert)
- Auto-downgrade rewrites expensive models to cheaper alternatives when budget threshold is reached
- Response cache (exact-match) reduces duplicate requests and latency
- Audit trail with checksummed halts for incident review
- Live cost dashboard at localhost:4100
- CLI ticker (relayplane watch) for real-time spend visibility
- Per-agent cost tracking via system prompt fingerprinting
- Over 11 providers supported: Anthropic, OpenAI, Google Gemini, xAI Grok, OpenRouter, and others
- No code changes: set ANTHROPIC_BASE_URL=http://localhost:4100 to route all traffic through proxy
- Open source (MIT), local by default, no telemetry required (opt-out available)
- Credential quarantine: evicts credential after 2 consecutive 401s
About Proxy
RelayPlane is an open-source (MIT) local proxy that sits between your AI agents and LLM providers (Anthropic, OpenAI, Google, etc.). It intercepts every API request, classifies the task (simple, agentic, judgment), and routes it to the most cost-effective model—automatically. Designed for teams using coding agents like Claude Code, Cursor, or Aider who need to control costs without changing application code. Unlike cloud gateways, RelayPlane runs locally by default, processes requests in <6ms, and requires only one environment variable (`ANTHROPIC_BASE_URL=http://localhost:4100`). It includes a live dashboard at localhost:4100 showing per-agent spend, model distribution, and cost guardrails. Telemetry is on by default (opt-out available). Key features: multi-credential pool (round-robins across Pro/Max/API keys to avoid rate limits and quota caps), quota-aware failover, anomaly detection (velocity spikes, token explosions, repetition loops), hard budget caps per agent/tenant/day, and a response cache. As of mid-2026, it is especially relevant for Anthropic users hit by per-token billing for third-party tools on Pro/Max subscriptions. Positioned as a cost-containment layer for AI agent infrastructure, RelayPlane contrasts with cloud-only gateways (e.g., Helicone, Lunary) by being fully local, open-source, and zero-config for agents that support base URL redirection. It's ideal for teams that want fine-grained control without a SaaS dependency.
Behind the Verdict
RelayPlane is the only local, open-source proxy we've seen that genuinely addresses the June 2026 Anthropic per-token billing shock. The credential pool—round-robining across Pro, Max, and API keys—is a clever way to stay under subscription caps without buying more. Anomaly detection catches runaway loops before they drain a budget, a real pain point with agentic tools. The live dashboard at localhost:4100 gives instant visibility. We'd reach for this when running multiple Claude Code instances or OpenClaw pipelines where costs can spiral. The 30-second install is not hyped—one npm command and an env var, and you're done. For teams already using cloud gateways like Helicone, RelayPlane offers a local alternative with no per-request fees. Where it falls short: it's CLI-only, so non-technical users will struggle. No SSO or RBAC, which limits enterprise adoption. The vendor page says the entire product is free (MIT), including Pro features—no paywalls. That's refreshing but raises questions about long-term sustainability. Compared to SaaS alternatives, you trade managed infrastructure for control and zero cost. For cost-sensitive teams using coding agents, RelayPlane is a no-brainer—but for those who want a fully managed solution with support, stick with cloud gateways.
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Use Cases
- Route simple classification and scoring tasks to Haiku or GPT-4o-mini, cutting costs by 60x compared to Opus
- Pool multiple Anthropic Pro and Max credentials to stay under per-subscription quota caps and avoid 429 errors
- Set a daily hard budget cap per agent to stop runaway agent bills that can reach $40/hour in API costs
- Monitor real-time cost per model and per agent via the local dashboard without telemetry or cloud login
- Enable anomaly detection to auto-kill agents stuck in repetition loops consuming tens of thousands of tokens
Models Under the Hood
as of 2026-07-15
Limitations
- RelayPlane runs locally by default, so the machine hosting the proxy must remain on and accessible to agents.
- The anomaly detection window is 100 requests—rapid bursts may pass before a flag is raised.
- Hard budget caps rely on proxy token counting, which may differ from provider billing.
- The free tier includes all features; no paid tier is required.
12-month cost
Project the real annual outlay, including the implied monthly cost when only an annual tier is published.
Vendor list price only. Add-on usage, seat overages, and contract minimums are surfaced under Hidden costs & gotchas.
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