Why we charge for what apps use

Tanzahost has no plans. There's no Tiny, Small or Large, no "Starter" with 10 GB, and no "upgrade to unlock". Every app pays for the memory and processor time it really uses, measured every minute and charged every hour from a prepaid wallet.

This post explains why we chose that, what it costs in a real example, and how we keep it from ever surprising you.

The owner's reasoning

Our first plan for Tanzahost had sizes, as most hosts do: pick a box, pay for the box. Our owner changed it. He never wanted plans like Tiny and Small; he wanted to charge for what's used, and not to limit the customer.

Two ideas sit inside that:

1. Don't sell a box. A plan sells you a box of a fixed size. Most small apps use a fraction of their box most of the time, and you pay for the empty part.

2. Don't stop a paying customer. A plan's limits are sales limits: hit the 10 GB and you must buy the next box. We'd rather your shop simply grows, and you pay for the extra it really uses.

How it works

The meter counts every process of an app: its web process, its workers and its scheduled tasks. A sleeping app pays for its storage only. A price list can also include a free amount of a meter for each project every month; the pricing page shows today's.

A worked example

Asha runs her Laravel shop, duka, in UK-01 · United Kingdom. Over a normal week it holds about 200 MB of memory and uses about 3% of one processor: busy at lunchtime, nearly idle at night.

A month of that use costs reading today's prices.

Now say a newspaper links to her shop, and for a day it uses ten times as much. She doesn't change anything, and nothing breaks: that day simply costs more, and the next day is back to normal. On a plan, she'd either have paid for the big box all year, or her shop would have slowed down on its best day.

Limits: the part that keeps your wallet safe

"Pay for what you use" sounds risky if you've ever had a surprise bill. So every app also has limits: the most memory and the most processor time it may use, which you set with two sliders.

Limits cost nothing by themselves. They're ceilings, not sizes:

• Asha sets duka's limits to 1 GB of memory and 1 processor. Even if her app used both limits fully, every hour of the month, it could never cost more than reading today's prices. The dashboard shows that ceiling next to the sliders.

• A bug that eats memory, or a loop that spins the processor, hits the limit instead of her wallet. When an app reaches its memory limit, we tell her, with a button to raise it.

• Changing a limit never restarts the app.

There's a second safety net for the whole account:

• A spending cap: the most a month may cost. When it's reached, we tell you, and nothing new can be added until next month. You can also choose to stop your apps at the cap.

• Reminders: your wallet shows about how many days it lasts at today's use, and we remind you when 7, 3 and 1 days are left.

• The price before every choice: before you add an app or change its limits, you see the rates and an estimate for the month, from the app's own use over its last 7 days, or from similar apps for a new one.

Compared with fixed plans

Fixed plans have real strengths, and we should say so:

If you need the exact same number on every invoice, a fixed plan is simpler. Our answer is to make the number predictable instead: an estimate before you start, a ceiling you choose for each app, and a cap for the month.

What this means for you

You choose how much an app may use, not how much you'll pay for in advance. A small site that sleeps at night costs very little. A busy shop pays for being busy. Nobody pays for space they never used, and nobody gets stopped for growing.

See today's rates on our pricing page, or read how billing works.