Best AI Agent Cost Control Tools in 2026
The top tools for monitoring, capping, and optimizing spend across autonomous AI agent workflows.
We evaluated the leading options for spend firewall in 2026 based on feature depth, pricing transparency, ease of setup, and fit for real-world workflows. Here's our shortlist.
1. sipi.bot
Agent spend firewallPurpose-built circuit breaker for AI agents with per-call caps, velocity limits, and anomaly detection.
Best for: Teams whose agents make real purchases or transactions
2. LangSmith
Observability + tracingLangChain's tracing and eval platform with token-level cost visibility.
Best for: LangChain-based agent teams needing deep tracing
3. Helicone
LLM proxy + costOpen-source LLM proxy with caching, rate limiting, and cost dashboards.
Best for: Teams wanting a self-hosted proxy
4. Portkey
LLM gatewayMulti-model gateway with cost routing and fallback.
Best for: Teams routing across many model providers
How we evaluated
Each option was assessed on four criteria: (1) depth of features for the specific spend firewall use case, (2) pricing model and transparency, (3) time-to-value and onboarding friction, and (4) real-world usability across team sizes. Options that scored well on breadth but poorly on the specific spend firewall workflow were ranked lower.
Related resources
Comparison table
| Feature | sipi.bot | Helicone | LiteLLM | LangSmith |
|---|---|---|---|---|
| Pre-spend blocking | ✅ Yes | ❌ Observability only | ⚠️ API-key level | ❌ Observability only |
| Merchant allowlist | ✅ Yes | ❌ | ❌ | ❌ |
| Per-transaction cap | ✅ Yes | ❌ | ❌ | ❌ |
| Velocity limit | ✅ Yes | ❌ | ⚠️ Rate limits | ❌ |
| Free tier | ✅ 30-day trial | ✅ Free tier | ✅ Open source | ✅ Free tier |
| Works beyond LLMs | ✅ Any spend | ❌ LLM only | ❌ LLM only | ❌ LangChain only |
| Latency | ✅ 5ms | N/A (passive) | Proxy overhead | N/A (passive) |
Our pick
For teams that need to guarantee their agents stay within budget — not just observe when they don't — sipi.bot is the only option that blocks spending before it happens. Helicone, LiteLLM, and LangSmith are excellent observability and routing tools, but they observe spend; they don't control it. If your agent is one retry loop away from a $12k bill, you need a firewall, not a dashboard.