FluxMeter vs Lago
Real-time enforcement layer vs billing platform — they work together.
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Lago is an open-source billing platform for usage-based pricing, subscriptions, and invoicing. FluxMeter is not a replacement — it adds real-time enforcement and monetization intelligence on the LLM hot path, and can export usage to Lago.
| Capability | FluxMeter | Lago |
|---|---|---|
| Primary role | Pre-request budget check & token metering | Billing, invoicing, subscriptions, plans |
| Runs on LLM request path | Yes — blocks calls before tokens burn | No — billing happens after usage is recorded |
| Agent loop protection | Sub-second cutoff for runaway agents | Relies on upstream enforcement or credit limits |
| Usage export | First-class Stripe/Metronome/Orb (v2.8) + Lago and more | Receives usage events from meters |
| Customer billing queries | Period, day, session, span, dim usage — no warehouse (dims v2.8) | Customer portal & invoice history |
| Hierarchy caps & soft alerts | Caps + reserve?parent_span_id= (v2.8) + BUDGET_WARN ladder (v2.7) | Plan credits & dunning in billing |
| Per-key API budgets | Budget per customer API key (v2.8) | Plan / subscription entitlements |
| Monetization intelligence | Root cause, unit economics, simulation, reports (3.0+) | Customer portal & invoice history |
| Tiered pricing | Flat, volume, graduated token pricing | Plan tiers & usage-based billing |
| LLM provider coverage | 20+ models with SDK track_* helpers | Provider-agnostic event ingestion |
| Self-hosted | Yes — Lite or Full mode | Yes — open-source billing platform |
| Customer-facing billing UI | No — infrastructure layer | Yes — plans, invoices, customer portal |
| Streaming LLM holds | Reserve → reconcile for in-flight streams | Billed on ingested usage events |
| License | Apache 2.0 | AGPLv3 (open source) |
Use FluxMeter + Lago when…
- You use Lago for billing but need instant budget enforcement on LLM calls
- Prepaid token wallets must block the next request, not the next invoice cycle
- Agent loops need sub-second checks that Lago alone cannot provide on the hot path
Use Lago alone when…
- Post-paid or invoice-based billing with no real-time cutoff requirement
- Usage metering latency of minutes is acceptable for your product
- You only need billing and invoicing without LLM-specific enforcement