Is a cron job enough to track API balances?

For two or three providers with balance endpoints, yes. It stops being enough when you need per-call cost, providers without a balance API, burn rates that ignore top-ups, alerts that don't repeat every hour, or a view your coding agent can query.

Argus vs a cron job and a spreadsheet

Polling balance endpoints yourself is a weekend project. Here's the honest list of what it takes and what you end up maintaining.

For two or three providers with a balance endpoint, a cron job writing to a spreadsheet works and costs nothing. Past that you're maintaining a connector per provider, each with its own auth header and response shape, plus burn-rate math, alert de-duplication and per-call capture for the providers that have no billing API. That's what Argus is.

The weekend version

# crontab: hourly balance snapshot to a CSV
0 * * * * ~/bin/snapshot.sh >> ~/api-balances.csv

# snapshot.sh
ts=$(date -u +%FT%TZ)
or=$(curl -sf https://openrouter.ai/api/v1/credits -H "Authorization: Bearer $OPENROUTER_API_KEY" \
  | jq '.data.total_credits - .data.total_usage')
fc=$(curl -sf https://api.firecrawl.dev/v2/team/credit-usage -H "Authorization: Bearer $FIRECRAWL_API_KEY" \
  | jq '.data.remainingCredits')
echo "$ts,openrouter,$or"
echo "$ts,firecrawl,$fc"

Chart the CSV and you can see a balance fall. That's genuinely useful, and if it's all you need, keep it.

What it grows into

You need	DIY	Argus
A connector per provider	Yours to write and keep working	28 maintained connectors
Auth quirks	X-KEY, APIKEY, apikey, ?api=, x-api-version…	Handled
Burn rate	Diff readings, ignore top-ups	Built in
Providers with no billing API	Capture and price each call	SDK and rate catalog
Alerts	Fire once, re-arm on clear	Email, with thresholds per rule
Agent access	Write an MCP server	Hosted MCP server
Cost	Your time	Free to $1,000 tracked, then $39 and $149 a month

Where DIY is better

Free, and nothing leaves your machine. No third party holds your provider keys.
Exactly the fields you care about, in the tool you already use.
No vendor to outlive.

Where Argus is better

Every quirk is already handled: Hunter's available is an allowance, Tavily reports usage, PDL hides the balance in headers. The integration pages list them all.
Per-call cost for providers with no billing API, priced from a maintained rate catalog.
Runway, spend spikes and rate-limit headroom as alerts, not columns you have to read.
Your coding agent can query it over MCP.

Questions

Is a cron job enough to track API balances?: For two or three providers with balance endpoints, yes. It stops being enough when you need per-call cost, providers without a balance API, burn rates that ignore top-ups, alerts that don't repeat every hour, or a view your coding agent can query.