Helicone tracks tokens. Stax tracks your entire AI bill.
Helicone, Langfuse, and Portkey are observability tools built for engineers. They watch the API call. Stax watches the invoice — API spend (OpenAI, Anthropic, Google AI, Mistral) and subscription spend (Cursor, Copilot, ChatGPT Business, Perplexity) — at one flat $49/mo that doesn't climb when your spend does. Four of those vendors expose admin APIs we sync nightly (OpenAI, Anthropic, Cursor, Copilot). The other four still need a 30-second monthly invoice upload — we'll flip them to live syncs the day those vendors ship admin APIs.
Stax vs Helicone, Langfuse, Portkey.
| Feature | SStax $49/mo flat | HHelicone usage-based | LLangfuse usage + seats | PPortkey usage + seats |
|---|---|---|---|---|
| Pricing modelhow the bill is calculated | Flat $49/mo · unlimited providers, unlimited spend tracked | Per-event pricing above 10K req/mo free tier | Per-observation tiers + per-seat add-ons | Per-request tiers + per-seat add-ons |
| Tracks API spendOpenAI, Anthropic, Google AI, Mistral | ✓Yes— OpenAI + Anthropic live; Google AI & Mistral via monthly invoice upload | ✓Yes | ✓Yes | ✓Yes |
| Tracks subscription toolsCursor, Copilot, ChatGPT Business, Perplexity | ✓Yes— Cursor + Copilot live; ChatGPT Business & Perplexity via monthly invoice upload | —No | —No | —No |
| Flat pricingcost doesn't rise with usage | ✓Yes— $49/mo regardless of scale | —No | —No | —No |
| Target audiencewho the UX is built for | Founders, CTOs, CFOs — finance-first views, plain English | Engineers — prompt traces, latency, eval flows | Engineers — observability, evals, datasets | Engineers — gateway routing, request logs |
| Setup timepaste keys to first chart | 4 minutes · billing-key paste, no SDK | SDK install · proxy or middleware | SDK install · code instrumentation | Gateway re-routing of API traffic |
| Self-serve dashboardsign up, see real numbers same day | ✓Yes | ✓Yes | ✓Yes | ✓Yes |
| Receipt-grade exportsPDF / CSV finance can hand the accountant | ✓Yes— per-tag, per-team, monthly | ~CSV of events | ~CSV of traces | ~CSV of logs |
Three things every competitor misses.
API-only is half the bill.
The average AI-forward team spends as much on Cursor seats, Copilot seats, and ChatGPT Business seats as it does on raw API tokens — often more. Observability tools watch the token meter and miss the subscription line entirely. If you only see half the bill, you can't make a budget. Stax pulls both in the same view.
Engineer UX, finance question.
Helicone, Langfuse, and Portkey are well-built — for the engineer debugging a prompt. The person who has to answer "why is the AI line $7,400 this month?" is rarely that engineer. Stax is built for the founder, CTO, or CFO who needs the answer in dollars, by team, by month, without learning a tracing tool.
Variable pricing punishes growth.
Usage-based pricing on a cost-tracking tool is the worst possible incentive. The month your AI bill doubles is the month your cost-tracker bill also goes up. Stax is flat $49/mo, regardless of providers connected or dollars tracked. Cost control software shouldn't get more expensive the moment you need it most.
What it costs to track $5,000/mo of AI spend.
A hypothetical mid-stage team: ~$5K/mo across OpenAI + Anthropic API and a half-dozen Cursor + Copilot seats. Roughly 2M API requests, ~50K traced events.
Heads up · these are estimates Competitor figures below are extrapolated from each vendor's public pricing tables — we have not negotiated, audited, or scraped their billing systems. Pricing changes; verify on the vendor's site before you sign anything. The dollar amounts are directional. The point is the shape: every competitor scales with your spend; Stax doesn't.
| Tool | Pricing basis | What's covered | Monthly cost | vs Stax |
|---|---|---|---|---|
| SStax · Pro | Flat $49/mo | API providers + subscriptions, unlimited spend tracked | $49 | flat |
| HHelicone · Pro | $20 base + per-event above 10K reqest. | API only · no subscription tracking | ~$200 | +$151 |
| LLangfuse · Core | Per-observation tiers + $59/seatest. | API only · trace-grade depth | ~$199 | +$150 |
| PPortkey · Production | Per-request tiers + $49/seatest. | API only · gateway routing included | ~$249 | +$200 |
See the full AI bill — in four minutes.
Paste your billing keys, watch API spend and subscription spend stitch into one view. Flat $49/mo, no per-event metering, no per-seat creep.