> ## Documentation Index > Fetch the complete documentation index at: https://docs.flex.ai/llms.txt > Use this file to discover all available pages before exploring further. # Limits and remaining credit for the calling key > Returns the calling key's configured limits and credit state: rate limits (RPM/TPM), cumulative spend, budget ceiling, and remaining budget — so a client can distinguish "the model is unhealthy" from "I'm rate-limited / out of credits" without admin access. The key in the `Authorization` header sees only itself. This endpoint is **budget-exempt**: it keeps answering when the key is out of credits (that is exactly when you need it). Inference endpoints remain fully budget-gated. `remaining_budget_usd` is the same value the gateway's 402 `insufficient_balance` check enforces, floored at 0. `rate_limit` reports the key's *configured* limits — the same values the `x-ratelimit-*` headers on inference responses advertise; for live headroom in the current window, read `x-ratelimit-remaining-*` from those headers. ## OpenAPI ````yaml /inference-api/openapi.yaml get /v1/flex/key openapi: 3.1.0 info: title: FlexAI Inference API version: 1.0.0 description: | OpenAI-compatible inference API for text, code, reasoning, vision, and embedding models hosted by FlexAI. Use any OpenAI SDK by pointing the `base_url` at this service. contact: name: FlexAI Support email: support@flex.ai url: https://docs.flex.ai/inference-api/overview servers: - url: https://tokens.flex.ai description: Production security: - bearerAuth: [] tags: - name: Chat description: Chat completions (streaming, tool use, vision). - name: Completions description: Legacy text completions. - name: Embeddings description: Generate vector embeddings for text. - name: Models description: Discover available models. - name: Usage description: Programmatic spend and quota for the calling key. paths: /v1/flex/key: get: tags: - Usage summary: Limits and remaining credit for the calling key description: | Returns the calling key's configured limits and credit state: rate limits (RPM/TPM), cumulative spend, budget ceiling, and remaining budget — so a client can distinguish "the model is unhealthy" from "I'm rate-limited / out of credits" without admin access. The key in the `Authorization` header sees only itself. This endpoint is **budget-exempt**: it keeps answering when the key is out of credits (that is exactly when you need it). Inference endpoints remain fully budget-gated. `remaining_budget_usd` is the same value the gateway's 402 `insufficient_balance` check enforces, floored at 0. `rate_limit` reports the key's *configured* limits — the same values the `x-ratelimit-*` headers on inference responses advertise; for live headroom in the current window, read `x-ratelimit-remaining-*` from those headers. operationId: getKey responses: '200': description: Successful response content: application/json: schema: type: object required: - object - currency - key_name - spend_usd - max_budget_usd - remaining_budget_usd - rate_limit - expires_at - generated_at properties: object: type: string enum: - key currency: type: string enum: - USD key_name: type: string nullable: true description: Masked display name ("sk-...abcd"); never the full key. spend_usd: type: number max_budget_usd: type: number nullable: true description: >- Budget ceiling for this key; null when no per-key ceiling is configured. remaining_budget_usd: type: number nullable: true description: >- max_budget_usd - spend_usd, floored at 0; null when max_budget_usd is null. rate_limit: type: object required: - rpm - tpm properties: rpm: type: integer nullable: true description: >- Requests per minute; null when no per-key limit is configured. tpm: type: integer nullable: true description: >- Tokens per minute; null when no per-key limit is configured. expires_at: type: string format: date-time nullable: true description: When this key expires; null means it never expires. generated_at: type: string format: date-time '401': $ref: '#/components/responses/Unauthorized' '403': description: The key is blocked. content: application/json: schema: $ref: '#/components/schemas/Error' '429': $ref: '#/components/responses/RateLimited' '502': description: Upstream authentication service unavailable. Retry shortly. content: application/json: schema: $ref: '#/components/schemas/Error' components: responses: Unauthorized: description: Missing or invalid API key. content: application/json: schema: $ref: '#/components/schemas/Error' RateLimited: description: | Per-key RPM exceeded. Response includes `Retry-After` and `x-ratelimit-*` headers. headers: Retry-After: schema: type: integer description: Seconds until the next window. x-ratelimit-limit-requests: schema: type: integer x-ratelimit-remaining-requests: schema: type: integer x-ratelimit-reset-requests: schema: type: integer content: application/json: schema: $ref: '#/components/schemas/Error' schemas: Error: type: object required: - error properties: error: type: object required: - message - type properties: message: type: string type: type: string example: invalid_request_error code: type: string description: | Stable machine-readable code for the failure. Present on most error paths; OMITTED on FastAPI default-validation bodies. Do not assume always present. doc_url: type: string format: uri description: | FlexAI extension. Link to the relevant dashboard / docs page for the failure mode (e.g. invalid key → /dashboard/keys). Present on auth and quota errors. securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: sk-xxxx description: | Virtual API key. Create one from the [FlexAI dashboard](https://tokens.flex.ai/dashboard/keys). Pass as `Authorization: Bearer sk-xxxx`. ````