Negotiate the best match
API · /negotiate-api
Content Negotiation API
healthy
4,718 Subscribers
HTTP content negotiation as an API. The parse endpoint reads an Accept, Accept-Language, Accept-Encoding or Accept-Charset header — with quality (q) values and parameters — into a clean list ranked by the client's preference. The negotiate endpoint takes that header plus the list of values your server can actually serve and returns the single best match, along with the full ranked result and the entry that matched each candidate. It applies the correct rules for each kind: media-type type and subtype wildcards (text/*, */*), RFC 4647 language-range matching (a request for en matches your en-US, and en-US falls back to en), and exact matching with a * wildcard for encodings and charsets — and a q=0 entry correctly rejects a value. Everything runs locally and deterministically, so it is instant and private. Ideal for i18n middleware and locale selection, API versioning by media type, response-format and compression selection, CDNs, proxies and edge functions. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This negotiates HTTP headers; to validate or decompose a single BCP-47 language tag use a BCP-47 API.
api.oanor.com/negotiate-api
API health
healthy- Uptime
- 100.00%
- Server probes · 24h
- Avg latency
- 79 ms
- Server probes · 24h
- Subscribers
- 4,718
- active
- Total calls
- 57
- last 7 days
Pricing
Pick a tier — billed monthly, cancel anytime.
Free
Free
- 2,335 calls / month
- 2 requests / second
- Hard cap (429 above quota, no overage)
- 2,335 calls/month
- 2 req/sec
- Parse + negotiate
- No credit card
Starter
€3.85 /month
- 11,850 calls / month
- 8 requests / second
- Hard cap (429 above quota, no overage)
- 11.85k calls/month
- 8 req/sec
- Language + media-type + encoding
- Email support
Pro
€23.75 /month
- 169,500 calls / month
- 20 requests / second
- Hard cap (429 above quota, no overage)
- 169.5k calls/month
- 20 req/sec
- i18n / proxy / edge pipelines
- Priority support
Mega
€61.75 /month
- 890,000 calls / month
- 50 requests / second
- Hard cap (429 above quota, no overage)
- 890k calls/month
- 50 req/sec
- Platform scale
- Dedicated SLA
Built by
Related APIs
Other APIs with overlapping tags.
MIME Types API
The canonical MIME / media-type database (the jshttp mime-db used by Express and most of the Node ecosystem: IANA + Apache + nginx), served from memory — no key. Resolve a media type to its file extensions, charset and compressibility; reverse-lookup the media type(s) for a file extension (e.g. png → image/png); and search or list types by source. 2,600+ media types, 1,000+ with file extensions. Lean, predictable JSON. Ideal for upload validation, Content-Type resolution, file-type detection, download handlers and developer tooling.
api.oanor.com/mimetypes-api
CORS API
Build correct CORS response headers and evaluate preflight requests — without re-reading the spec every time. The headers endpoint turns a simple policy (allowed origins, methods, request headers, whether credentials are allowed, a preflight max-age and any exposed response headers) into the exact set of Access-Control-* headers to return, and it handles the parts people get wrong: you cannot combine a wildcard origin with credentials, so it reflects the specific request origin and adds Vary: Origin instead; it omits the allow-origin header when an origin is not on your list; and it warns when a configuration would not behave as expected. The check endpoint takes an incoming request — its Origin, the (requested) method and the Access-Control-Request-Headers — and tells you whether it would pass CORS, the precise reason if it fails, and the response headers you should send back. Everything is computed locally and deterministically, so it is instant and private. Ideal for API gateways and backends, edge and serverless functions, debugging browser CORS errors, and getting a security policy exactly right. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This builds and checks the headers; it does not make a cross-origin request — to inspect a live site's security headers use a security-headers API.
api.oanor.com/cors-api
Client IP API
Find the real client IP behind proxies, CDNs and load balancers. The client endpoint takes an X-Forwarded-For list (or an RFC 7239 Forwarded header) together with a count of proxies you trust, and returns the actual client address — stripping the trusted proxies from the right-hand side so that a spoofed left-most value cannot fool you — along with the full ordered hop chain, the left-most and right-most entries and the address family. The parse endpoint decomposes a Forwarded header into its for/by/host/proto hops, or an X-Forwarded-For header into its ordered list of addresses, stripping ports and IPv6 brackets so you get clean IPs. Getting this right matters for security: trusting the wrong entry lets clients spoof their IP, so the trusted-proxy model returns the first address you did not put there yourself. Everything is computed locally and deterministically, so it is instant and private. Ideal for reverse proxies and API gateways, rate limiting and abuse prevention, audit logging and analytics, geo and fraud checks, and any backend sitting behind a load balancer. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This parses forwarding headers to find the client IP; to geolocate that IP use an IP-geolocation API.
api.oanor.com/clientip-api
Content-Disposition API
Parse and build HTTP Content-Disposition headers (RFC 6266, with RFC 5987 filename* encoding). The parse endpoint reads a header into its disposition type (attachment, inline or form-data), its filename — correctly decoding the extended filename*=UTF-8''… form and preferring it over a plain filename exactly as the specification requires — the form-data field name, and any remaining parameters. The build endpoint assembles a correct header from simple fields and, when a filename contains non-ASCII characters (accents, emoji, CJK), automatically emits both an ASCII fallback filename and the percent-encoded filename*, so every browser shows the right download name while older clients still work. Everything is computed locally and deterministically, so it is instant and private — no file is ever fetched or stored. Ideal for file-download and upload endpoints, object storage and CDNs, content gateways and proxies, email and multipart handling, and debugging why a download is mis-named. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This builds and parses the header string itself; it does not serve a file.
api.oanor.com/contentdisposition-api
Frequently asked questions
Quick answers about pricing, quotas, and integration.
How do I get an API key for Content Negotiation API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Content Negotiation API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Content Negotiation API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does Content Negotiation API cost?
Content Negotiation API has a free tier with 100 calls / month. Paid plans start at €3.85 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is Content Negotiation API GDPR-compliant?
All requests to Content Negotiation API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.
Pick an endpoint from the list on the left to see its details and try it.
Code snippets
Sign up to get an API key, then call any path under your slug.
curl https://api.oanor.com/negotiate-api/SOME_PATH \
-H "x-oanor-key: oanor_test_..."const res = await fetch("https://api.oanor.com/negotiate-api/SOME_PATH", {
headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();$ch = curl_init("https://api.oanor.com/negotiate-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);import requests
r = requests.get(
"https://api.oanor.com/negotiate-api/SOME_PATH",
headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())Ratings
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