OpenAI API vs Postman
Frontier models: GPT-5, o-series reasoning, image, audio, embeddings
vs. The world's most popular API platform — 30M+ developers
Pricing tiers
OpenAI API
Free Tier (Trial)
$5 free credit for new accounts. Rate-limited.
Free
Pay-as-you-go
No monthly min. Per-token pricing by model.
$0 base (usage-based)
Usage Tiers (1-5)
Automatic tier promotion based on cumulative spend. Higher tiers = higher rate limits + new model access.
$0 base (usage-based)
Enterprise
Custom. Priority access, SLA, dedicated capacity.
Custom
Postman
Free
$0. 3 users. 1,000 collection runs/mo. Unlimited collections. 1,000 calls/mo to mock servers. 14-day history.
Free
Basic
$19/user/mo. 10,000 collection runs, 50 integrations, 60-day history, integrations.
$19/mo
Professional
$39/user/mo. 250,000 runs, API mocking, monitoring, version tags, governance lite.
$39/mo
Enterprise
$99/user/mo (Ultimate). Unlimited runs, SSO/SAML, RBAC, IP allowlist, private cloud, audit.
$99/mo
Free-tier quotas head-to-head
Comparing free-tier on OpenAI API vs free on Postman.
| Metric | OpenAI API | Postman |
|---|---|---|
| No overlapping quota metrics for these tiers. | ||
Features
OpenAI API · 12 features
- Assistants API — Stateful assistants with tools, threads, file search.
- Batch API — 50% discount for async processing within 24h.
- Chat Completions API — Classic /v1/chat/completions endpoint.
- Files API — Upload docs for retrieval, fine-tuning, batch.
- Fine-Tuning — Supervised + DPO fine-tuning for GPT-4o, GPT-4.1, GPT-4o-mini.
- Function Calling — JSON-schema tool calling; parallel calls supported.
- Moderation — Safety classifier API (free).
- Prompt Caching — Auto-cache repeated prefixes; 50% cheaper cached hits.
- Realtime API — WebSocket streaming voice + text with low latency.
- Responses API — Stateful conversational API.
- Structured Outputs — Enforced JSON schema compliance.
- Vision — Image input for GPT models.
Postman · 17 features
- API Documentation — Public + private docs from collections.
- API Versioning — Manage multiple API versions.
- Collection Runner — Run N iterations with data.
- Collections — Saved request groups + runners.
- Desktop App — Native Mac/Win/Linux.
- Environments — Per-env variables.
- Flows (low-code) — Visual workflow builder.
- Governance — API design rules enforcement.
- Mock Servers — Auto-generated mocks.
- Monitors — Scheduled collection runs + alerts.
- Newman CLI — CI/CD collection runner.
- Postman AI — Generate tests + docs with AI.
- Pre-request / Test Scripts — JS scripts + assertions.
- Public API Network — Discoverable APIs marketplace.
- Request Builder — GUI for any HTTP request.
- Request History — Per-user request log.
- VS Code Extension — Requests inside VS Code.
Developer interfaces
| Kind | OpenAI API | Postman |
|---|---|---|
| CLI | — | newman (CLI) |
| SDK | openai-dotnet, openai-go, openai-node, openai-python | — |
| REST | OpenAI REST API | Postman API |
| MCP | OpenAI MCP | — |
| OTHER | Realtime API (WebSocket) | Postman Desktop, Postman VS Code Extension, Postman Web, Public API Network |
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