All three hand you a key for an email address. No card.
There is a moment that arrives once you have used AI for a while: "I want to wire this into my own program, not just chat with it."
Then you open the API page and it asks for a credit card before it tells you anything. Putting a card down for a bill you cannot estimate is an uncomfortable trade.
Three services skip that step entirely. Email, verify, get a key. I signed up for all three and checked what the limits actually are.
Not sure what an API is? It is the channel your program uses to talk to an AI. Chatting on a website is a person using it directly; an API is your app or automation calling the model on your behalf.
Side by side
| OpenRouter | NVIDIA Build | Bytez | |
|---|---|---|---|
| Credit card | Not needed | Not needed | Not needed |
| Free allowance | Free models, always | 1,000 credits on signup | $1 every 4 weeks |
| Rate limit | 20/min · 50/day | ~40/min | 10/sec · 1 concurrent |
| Models | 57 free endpoints | 124 (57 free) | 220,000 (free: under 7B) |
| Difficulty | Easiest | Easy | Medium |
1. OpenRouter — start here
A broker that puts many companies' models behind one address. Any model with :free after its name runs without credits.
- Limits: 20 requests per minute, 50 per day
- To raise them: a one-time $10 of credit lifts the daily cap to 1,000
The reason it is the right first stop: switching models is a one-string change. You do not learn a different SDK per vendor.
50 a day goes faster than it sounds. An afternoon of testing will finish it. If you are building anything serious, treat the $10 as effectively required and save yourself the interruption.
2. NVIDIA Build — the most credits
NVIDIA's own model catalog. At the time I checked it listed 124 models, 57 of them marked as free endpoints.
- Signing up gives you 1,000 credits
- Registering with a company email adds 4,000 more (5,000 total)
- Rate: around 40 per minute, varying by model and traffic
The flow is pleasant: test a model in the browser, and if you like it, take an nvapi- key from that same screen.
The catch matters though — when the credits are gone, they are gone. Nothing refills monthly. That is the sharpest difference from OpenRouter.
3. Bytez — enormous catalog, tight leash
One API key reaching 220,000 models.
- Free plan: $1 of credit every 4 weeks
- Restricted to open models under 7B, one request at a time
- Credits expire after those 4 weeks
Honestly, the free plan is a taste test. A dollar does not last. Its real value shows up when the model you need exists nowhere else. Serious use starts at $3/month.
So where do you start?
- OpenRouter. Simplest signup, free models stay free. Best place to get your bearings.
- NVIDIA Build when 50/day stops being enough. 1,000 credits buys a lot more experimentation.
- Bytez when you need a model the other two do not carry. A last resort, and a good one.
Before you start
All three give you a key for an email address alone. Try them, and drop the ones that do not fit.
But "free" does not mean unlimited. All three have ceilings, and knowing yours before you build is what keeps a sudden wall from derailing an afternoon.
The short version
AI coding workflows, tested on real work — not demos. New posts weekly.