Important OpenAI Compatibility Limitations
API Behavior
Here are the most substantial differences from using OpenAI:- Multimodal input (images/audio) is not supported and will be ignored.
- Prompt caching is not supported.
- Most unsupported fields are silently ignored rather than producing errors. These are all documented below.
Detailed OpenAI Compatible API Support
Request Fields
Simple Fields
| Field | Support Status |
|---|---|
| model | Use “speed” |
| response_format | Fully supported |
| stream | Fully supported |
| max_tokens | Ignored |
| max_completion_tokens | Ignored |
| stream_options | Ignored |
| top_p | Ignored |
| parallel_tool_calls | Ignored |
| stop | Ignored |
| temperature | Ignored |
| n | Ignored |
| logprobs | Ignored |
| metadata | Ignored |
| prediction | Ignored |
| presence_penalty | Ignored |
| frequency_penalty | Ignored |
| seed | Ignored |
| service_tier | Ignored |
| audio | Ignored |
| logit_bias | Ignored |
| store | Ignored |
| user | Ignored |
| modalities | Ignored |
| top_logprobs | Ignored |
| reasoning_effort | Ignored |
Tools / Functions Fields
Tools are ignored.Messages Array Fields
| Field | Support Status |
|---|---|
| messages[].role | Fully supported |
| messages[].content | Fully supported |
| messages[].name | Fully supported |
| messages[].tool_calls | Ignored |
| messages[].tool_call_id | Ignored |
| messages[].function_call | Ignored |
| messages[].audio | Ignored |
| messages[].modalities | Ignored |
Response Fields
| Field | Support Status |
|---|---|
| id | Always empty |
| choices[] | Will always have a length of 1 |
| choices[].finish_reason | Always empty |
| choices[].index | Fully supported |
| choices[].message.role | Fully supported |
| choices[].message.content | Fully supported |
| choices[].message.tool_calls | Always empty |
| object | Always empty |
| created | Fully supported |
| model | Always empty |
| finish_reason | Always empty |
| content | Fully supported |
| usage.completion_tokens | Always empty |
| usage.prompt_tokens | Always empty |
| usage.total_tokens | Always empty |
| usage.completion_tokens_details | Always empty |
| usage.prompt_tokens_details | Always empty |
| choices[].message.refusal | Always empty |
| choices[].message.audio | Always empty |
| logprobs | Always empty |
| service_tier | Always empty |
| system_fingerprint | Always empty |
Error Message Compatibility
The compatibility layer maintains approximately the same error formats as the OpenAI API.Header Compatibility
While the OpenAI SDK automatically manages headers, here is the complete list of headers supported by Parallel’s API for developers who need to work with them directly.| Field | Support Status |
|---|---|
| authorization | Fully supported |
| x-ratelimit-limit-requests | Ignored |
| x-ratelimit-limit-tokens | Ignored |
| x-ratelimit-remaining-requests | Ignored |
| x-ratelimit-remaining-tokens | Ignored |
| x-ratelimit-reset-requests | Ignored |
| x-ratelimit-reset-tokens | Ignored |
| retry-after | Ignored |
| x-request-id | Ignored |
| openai-version | Ignored |
| openai-processing-ms | Ignored |