OpenTopoData API

Free elevation API with no key: ground elevation for any coordinates from multiple global datasets including SRTM, ASTER and ETOPO1. Self-hostable. Tested.

No API key requiredHTTPSFree tier

Endpoint tested and returned HTTP 200 on 20 Aug 2026

What is the OpenTopoData API?

OpenTopoData is a free, key-free elevation API returning ground elevation for any coordinates, with a choice of global datasets including SRTM, ASTER, EU-DEM and ETOPO1 for ocean bathymetry.

Elevation lookup is a common need — for hiking apps, drone planning, flood modelling — and OpenTopoData covers it with no key, offering several datasets at different resolutions rather than a single opaque source.

Dataset choice genuinely matters. SRTM offers 30m resolution but only covers land between roughly 60°N and 56°S; ETOPO1 is far coarser but global and includes ocean depths. Picking the wrong one for your latitude returns nulls.

Quick facts

Base URL: https://api.opentopodata.org/v1
Authentication: No API key required on the public instance.
Rate limit: 1,000 calls per day and 1 call per second on the public instance.
Pricing: Free and open source; self-host for unlimited use.
CORS: Not enabled — call it from your server
Official docs: Read the docs

How to use the OpenTopoData API

Every request below was executed against the live API on 20 Aug 2026, and the response shown is the real body it returned — not an illustration.

1. Look up elevation for coordinates

GET https://api.opentopodata.org/v1/etopo1?locations=31.52,74.35

curl

curl 'https://api.opentopodata.org/v1/etopo1?locations=31.52,74.35'

JavaScript (fetch)

const res = await fetch("https://api.opentopodata.org/v1/etopo1?locations=31.52,74.35");
if (!res.ok) throw new Error(`Request failed: ${res.status}`);
const data = await res.json();
console.log(data);

Python (requests)

import requests

res = requests.get("https://api.opentopodata.org/v1/etopo1?locations=31.52,74.35", timeout=20)
res.raise_for_status()
print(res.json())

Response — HTTP 200

{
  "results": [
    {
      "dataset": "etopo1",
      "elevation": 216.0,
      "location": {
        "lat": 31.52,
        "lng": 74.35
      }
    }
  ],
  "status": "OK"
}

Parameters

Parameter	Type	Required	Description
`<dataset>`	path	Required	srtm30m, srtm90m, aster30m, eudem25m, etopo1, mapzen. `etopo1`
`locations`	string	Required	Pipe-separated lat,lng pairs. `31.52,74.35`
`interpolation`	string	Optional	nearest, bilinear or cubic. `bilinear`

Response fields

statusstring: OK on success.
resultsarray: One entry per requested location.
results[].elevationnumber: Elevation in metres above sea level; negative below.
results[].locationobject: The coordinates that were queried.
results[].datasetstring: Which dataset the value came from.

What you can build with the OpenTopoData API

Add elevation profiles to hiking or cycling routes
Plan drone flights with terrain awareness
Support flood and terrain modelling
Enrich geographic data with altitude

Common errors and how to fix them

elevation is null

The dataset does not cover those coordinates.

Fix: SRTM covers roughly 60°N to 56°S only. Use etopo1 for global coverage including polar regions and oceans.

429

Exceeded 1,000 calls per day or 1 per second.

Fix: Batch up to 100 locations per request with pipe separators, and cache — terrain does not change.

Unexpectedly coarse values

ETOPO1 is roughly 1.8km resolution.

Fix: Use srtm30m for land detail; etopo1 is for global and ocean coverage, not precision.

OpenTopoData API — frequently asked questions

Is OpenTopoData free?

Yes, the public instance is free with no API key at 1,000 calls per day. It is open source, so you can self-host for unlimited use.

Which dataset should I use?

srtm30m for detailed land elevation between 60°N and 56°S, eudem25m for Europe, and etopo1 for global coverage including polar regions and ocean depths.

Why is my elevation null?

The chosen dataset does not cover those coordinates. SRTM has no data above 60°N — switch to etopo1 for global coverage.

Can I look up many points at once?

Yes, pipe-separate up to 100 coordinate pairs in the locations parameter, which is far more efficient than individual requests.

Tools that pair with this API

JSON Formatter

Format, beautify and minify JSON online with 2-space, 4-space or tab indentation. Sort keys alphabetically and catch syntax errors instantly — free and private.

Unit Converter

Convert between units of length, weight, temperature, area, volume, speed, time and data storage instantly, with a swap button and common conversion tables.

Alternatives to OpenTopoData API

If OpenTopoData does not fit, these geolocation & ip apis cover similar ground. Every one was called before publishing, and each links to its own reference page with a working curl command and the response it returned.

API	What it does	Auth	CORS	Last verified
ipify	ipify is a free, unlimited API that returns your public IP address as text, JSON or JSONP. No key, no rate limit, IPv4 and IPv6 endpoints. Live curl example.	No key	Yes	19 Aug 2026
ip-api.com	Free IP geolocation API returning country, city, coordinates, timezone and ISP for any IP. No key on the free tier, 45 requests per minute. Tested curl example.	No key	Yes	19 Aug 2026
ipwho.is	Free IP geolocation API with HTTPS and no API key. Returns country, city, coordinates, timezone, currency and connection data. 10,000 requests/month free.	No key	Yes	19 Aug 2026
Nominatim (OpenStreetMap)	Free OpenStreetMap geocoding API: convert addresses to coordinates and back. No API key, open data, 1 request per second. Tested curl example and usage policy.	No key	No	19 Aug 2026
OSRM Routing	Free OSRM routing API with no key: driving, cycling and walking routes with distance, duration, turn-by-turn steps and geometry from OpenStreetMap. Tested.	No key	Yes	20 Aug 2026
PDOK Locatieserver	Free official Dutch geocoding API with no key: search addresses, streets, postcodes and place names from the BAG, with RD and WGS84 coordinates. Tested example included.	No key	Yes	21 Aug 2026

All Geolocation & IP APIs

OpenTopoData is an independent third-party service and is not affiliated with ByteTools or ByteVancer. Details on this page were verified on 20 Aug 2026; always check the official documentation before relying on this API in production, as terms and limits can change.