The Day /models Returns 200 but generateContent Returns 403 — Decide Your Triage Order Before It Happens
A triage order for the case where listing models succeeds with 200 but generation fails with 403 permission_denied. Includes a small diagnostic script that checks key, project, and billing in turn, why you should not retry a 403, and how to assemble what support needs.
Why count_tokens Lies: 5 Reasons Your Gemini API Bill Is Higher Than You Estimated — A Reconciliation Playbook
count_tokens said 1,200 tokens. Cloud Console billed you for 4,800. I made the same mistake building my first indie app on Gemini. This guide walks through the five hidden contributors — thinking, tools, multimodal, history, caching — and how to reconcile them with reproducible code.
Gemini API × Stripe — Production Usage-Based Billing for Indie AI SaaS
A complete guide to building a usage-based billing system for your Gemini API SaaS using Stripe Metered Billing and webhooks — production patterns included.
Architecting a Multi-Tenant SaaS on Gemini API — Tenant Isolation, Usage Metering, and Runaway Cost Defense in Production
A field-tested blueprint for serving Gemini API to multiple tenants on a single backend — covering tenant isolation choices, per-tenant rate limiting in Redis, request-level usage metering for billing, and runaway-cost defenses.
Track Gemini API Costs in Production with usageMetadata — A Per-Request Logging Pattern That Reconciles With Your Bill
A production pattern for capturing Gemini API's usageMetadata per request to attribute spend by endpoint, user, and model — hardened for the 3.5 Flash GA era where the default model can shift under you. Covers pricing keyed on resp.model_version and a nightly audit that flags model drift and unknown models before the invoice does.
Gemini API FAILED_PRECONDITION Error: Case-by-Case Diagnosis and Fixes
FAILED_PRECONDITION in Gemini API means 'the current system state doesn't allow this operation.' Learn to diagnose and fix all common causes: billing setup, API enablement, context cache expiry, and model access restrictions.
Gemini API Pricing & Billing [2026]: From Free Tier to Token Costs Explained
A clear breakdown of Gemini API pricing in 2026 — free tier limits, token-based billing, model cost comparisons, usage estimation, and spend cap setup to keep your costs under control.