> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lightdrift.ai/llms.txt
> Use this file to discover all available pages before exploring further.
# Plans and limits
> Understand credit purchases, automatic plan upgrades, and the request limits for each Lightdrift plan.
Lightdrift is pay-as-you-go. Your **credit balance** pays for searches, while your **plan** determines how many requests you can make and how many searches can run at once.
Check your current plan, limits, and progress toward the next plan in [Plan and limits](https://lightdrift.ai/dashboard/plan). Buy credit and view your balance in [Credits](https://lightdrift.ai/dashboard/billing).
## Plans at a glance
Plans are based on your cumulative credit purchases in USD. These are purchase thresholds, not monthly subscription prices.
| Plan | Total credit purchased | Requests per minute | Requests per day | Concurrent searches |
| ------- | ---------------------- | ------------------- | ---------------- | ------------------- |
| Promo | Less than \$10 | 30 | 1,000 | 2 |
| Starter | \$10 or more | 60 | 5,000 | 4 |
| Growth | \$100 or more | 300 | 25,000 | 10 |
| Scale | \$1,000 or more | 1,000 | 100,000 | 25 |
For custom limits, [contact us](mailto:hello@lightdrift.ai). If your account or API key has custom limits, they can differ from the standard plans above.
## How upgrades work
Add credit in [Credits](https://lightdrift.ai/dashboard/billing). Each credit purchase contributes to your cumulative purchase total.
Your plan upgrades automatically when the total reaches $10, $100, or \$1,000. You do not pay a separate upgrade fee.
The purchased credit remains available to pay for searches. Using your balance does not reduce your cumulative purchase total or lower your plan.
**Example:** You have purchased $5 and are on Promo. Purchase another $5 to reach $10 in total purchases and unlock Starter: 60 requests per minute, 5,000 per day, and 4 concurrent searches. That new $5 is added to your search balance.
Promotional credit and account adjustments do not count toward plan upgrades. Your available balance can therefore be different from the purchase total shown on your plan page.
## What each limit means
* **Requests per minute:** how many authenticated requests you can make in a minute window.
* **Requests per day:** how many authenticated requests you can make in a daily window.
* **Concurrent searches:** how many searches can be in progress at the same time across your account. Once a search finishes, its slot becomes available again.
Minute and daily request limits use fixed windows. Requests count toward these limits even when rejected; repeatedly retrying will not bypass the limit. A request limit is not a billing charge: failed searches are not charged.
With API keys, minute and daily counters are tracked per key. Images MCP connections authenticated through OAuth share a request counter for the account. Concurrent searches are counted across the account. Custom API-key limits may override the plan defaults.
## Search pricing and balance
A successful image search or similar-image search costs **\$0.02**. Retrieving image details is free. Higher plans increase request capacity; the request allowances do not include free searches.
You need both available credit and room within your limits to run a paid search. A high plan does not replace a credit balance. See [Images MCP](/guides/images-mcp) for tool pricing and [the search guide](/guides/search) for REST usage.
[Docs MCP](/guides/docs-mcp) reads public documentation and does not spend Lightdrift search credit.
## When a request is blocked
| Response | Meaning | What to do |
| --------------------------- | ----------------------------------------------- | ------------------------------------------------------------------------------------------------------ |
| `402` | Not enough credit for the search | Check your balance and [add credit](https://lightdrift.ai/dashboard/billing). |
| `429` — request limit | Minute or daily allowance reached | Wait for the `Retry-After` delay before retrying. Pace requests instead of sending them in bursts. |
| `429` — concurrent searches | Too many searches are already running | Wait for an active search to finish and respect `Retry-After`. Use a queue to limit parallel searches. |
| `503` with `gpu_warming` | The search service is starting after being idle | Wait about 30 seconds and retry. Startup can take longer; the failed call is not charged. |
## Headers for API integrations
Use the response headers to pace REST requests. Headers available depend on the response; a concurrency rejection, for example, includes `Retry-After` and `X-Concurrency-Limit`.
| Header | Meaning |
| ----------------------- | -------------------------------------------------------------------------------------------------------------- |
| `X-RateLimit-Tier` | The effective plan for the request |
| `X-RateLimit-Limit` | The minute and daily request limits |
| `X-RateLimit-Remaining` | The smaller remaining allowance across the minute and daily windows |
| `X-RateLimit-Reset` | Seconds until the minute window resets; on a request-limit rejection, seconds until the blocking window resets |
| `X-Concurrency-Limit` | The effective limit for simultaneous searches |
| `Retry-After` | Seconds to wait before retrying a rejected request |
Your [dashboard plan page](https://lightdrift.ai/dashboard/plan) shows the account's plan defaults. API headers reflect the effective limits for a particular request, including custom key limits.