Free APIs for C# developers

C# and .NET call public APIs with HttpClient and System.Text.Json, both built into the framework, from console apps, ASP.NET back ends or Unity games.

Call a public API in C#

This example calls the Econdb API, which needs no API key. It's a live endpoint: our health check got JSON back from it on Oct 24, 2026.

using System.Net.Http;

using var http = new HttpClient { Timeout = TimeSpan.FromSeconds(10) };
var json = await http.GetStringAsync("https://www.econdb.com/api/");
Console.WriteLine(json);

Sending an API key in C#

Most free tiers need a key. Read it from an environment variable and send it as a header:

http.DefaultRequestHeaders.Authorization =
    new("Bearer", Environment.GetEnvironmentVariable("API_KEY"));
var json = await http.GetStringAsync("https://api.example.com/v1/items");

Best free APIs for C# in 2026

1
Bidledger API
Online · 279 ms
Every open public tender in the European Union, rebuilt daily from the official TED data.
- No API key needed
- Fast: 279 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
2
Dog Facts API
Online · 342 ms
Random dog facts. A free animals API by dukengn.github.io.
- No API key needed
- Fast: 342 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
3
Dog Facts API
Online · 356 ms
Random facts of Dogs. A free animals API by Dog API by kinduff.
- No API key needed
- Fast: 356 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
4
Econdb API
Online · 802 ms
Download economic and shipping data using Python.
- No API key needed
- Returns JSON at its URL
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
5
Icanhazip API
Online · 278 ms
The family of icanhaz sites help you get more information about your network connection.
- No API key needed
- Fast: 278 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
6
Index Agentica API
Online · 382 ms
Agent-first directory of skills, MCP servers, tools, protocols and APIs as JSON, markdown, llms.txt.
- No API key needed
- Fast: 382 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
7
ipwhois API
Online · 226 ms
IP geolocation with country, city, coordinates, ISP, timezone and flag data.
- No API key needed
- Fast: 226 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
8
Microlink.io API
Online · 378 ms
Extract structured data from any website.
- No API key needed
- Fast: 378 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
9
NASA POWER API
Online · 228 ms
Global solar and weather data for energy and agriculture.
- No API key needed
- Fast: 228 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
10
Open VSX API
Online · 270 ms
Search and access VS Code extensions from the Open VSX registry.
- No API key needed
- Fast: 270 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
11
OpenSanctions API
Online · 343 ms
Data on international sanctions, crime and politically exposed persons.
- No API key needed
- Fast: 343 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
12
PayCrunch API
Online · 278 ms
US wages for 1,008 occupations and by state, from BLS OEWS May 2025, static JSON, CC BY 4.0.
- No API key needed
- Fast: 278 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
13
Presend API
Online · 399 ms
Security and developer utility API -- malware, vulnerability, and domain checks, no signup.
- No API key needed
- Fast: 399 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
14
RubyGems API
Online · 360 ms
Ruby gem metadata, versions, dependencies and search.
- No API key needed
- Fast: 360 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
15
Statically API
Online · 324 ms
A free CDN for developers.
- No API key needed
- Fast: 324 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
16
BirkinBagStock API
Online · 1011 ms
Independent Hermès resale index: inventory, market prices, auction calendar and results.
- No API key needed
- Returns JSON at its URL
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
17
DefiLlama API
Online · 178 ms
Open and transparent DeFi data, TVL, coin prices, volumes, and yields.
- No API key needed
- Fast: 178 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
18D
DocStruct API
Online · 190 ms
AI extraction of invoices, receipts, bank statements & contracts into structured JSON/CSV.
- No API key needed
- Fast: 190 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
19
GBIF API
Online · 115 ms
Global Biodiversity Information Facility. A free science & math API by gbif.org.
- No API key needed
- Fast: 115 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
20
Helium API
Online · 377 ms
News with media bias scoring, balanced news synthesis, live market data, AI options pricing.
- No API key needed
- Fast: 377 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
21
L2 Calendar API
Online · 1046 ms
Lineage 2 private servers list with names, websites, chronicles, rates and opening dates.
- No API key needed
- Returns JSON at its URL
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
22
Legal Sandbox Georgia API
Online · 563 ms
Find verified legal specialists in Georgia from natural-language queries.
- No API key needed
- Returns JSON at its URL
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
23
Macrostrat API
Online · 694 ms
Geologic maps, rock columns and stratigraphy data.
- No API key needed
- Returns JSON at its URL
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
24
Modelfax API
Online · 328 ms
LLM pricing, context windows and deprecation dates, schema-validated and updated daily.
- No API key needed
- Fast: 328 ms response
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS
25
RemoteOK API
Online · 861 ms
Remote job board for digital nomads.
- No API key needed
- Returns JSON at its URL
- Callable from the browser (CORS)
- HTTPS
No authHTTPSCORS

Live JSON endpoints to try

These API URLs returned valid JSON in our latest check, so the C# example above works with any of them.

Econdb APIhttps://www.econdb.com/api/

using System.Net.Http;

using var http = new HttpClient { Timeout = TimeSpan.FromSeconds(10) };
var json = await http.GetStringAsync("https://www.econdb.com/api/");
Console.WriteLine(json);

BirkinBagStock APIhttps://birkinbagstock.com/.well-known/openapi.json

using System.Net.Http;

using var http = new HttpClient { Timeout = TimeSpan.FromSeconds(10) };
var json = await http.GetStringAsync("https://birkinbagstock.com/.well-known/openapi.json");
Console.WriteLine(json);

L2 Calendar APIhttps://l2calendar.com/api/servers

using System.Net.Http;

using var http = new HttpClient { Timeout = TimeSpan.FromSeconds(10) };
var json = await http.GetStringAsync("https://l2calendar.com/api/servers");
Console.WriteLine(json);

Legal Sandbox Georgia APIhttps://legal.ge/api/openapi.json

using System.Net.Http;

using var http = new HttpClient { Timeout = TimeSpan.FromSeconds(10) };
var json = await http.GetStringAsync("https://legal.ge/api/openapi.json");
Console.WriteLine(json);

Macrostrat APIhttps://macrostrat.org/api

using System.Net.Http;

using var http = new HttpClient { Timeout = TimeSpan.FromSeconds(10) };
var json = await http.GetStringAsync("https://macrostrat.org/api");
Console.WriteLine(json);

RemoteOK APIhttps://remoteok.com/api

using System.Net.Http;

using var http = new HttpClient { Timeout = TimeSpan.FromSeconds(10) };
var json = await http.GetStringAsync("https://remoteok.com/api");
Console.WriteLine(json);

Veabird APIhttps://veabird.com/api/v1

using System.Net.Http;

using var http = new HttpClient { Timeout = TimeSpan.FromSeconds(10) };
var json = await http.GetStringAsync("https://veabird.com/api/v1");
Console.WriteLine(json);

Verif Entreprise FR APIhttps://api-production-24833.up.railway.app

using System.Net.Http;

using var http = new HttpClient { Timeout = TimeSpan.FromSeconds(10) };
var json = await http.GetStringAsync("https://api-production-24833.up.railway.app");
Console.WriteLine(json);

AI Economics Tools APIhttps://piszczek.pl/tools/api

using System.Net.Http;

using var http = new HttpClient { Timeout = TimeSpan.FromSeconds(10) };
var json = await http.GetStringAsync("https://piszczek.pl/tools/api");
Console.WriteLine(json);

BlazePhoenix APIhttps://blazephoenix.xyz/api

using System.Net.Http;

using var http = new HttpClient { Timeout = TimeSpan.FromSeconds(10) };
var json = await http.GetStringAsync("https://blazephoenix.xyz/api");
Console.WriteLine(json);

Block Lottos APIhttps://blocklottos.com/openapi.json

using System.Net.Http;

using var http = new HttpClient { Timeout = TimeSpan.FromSeconds(10) };
var json = await http.GetStringAsync("https://blocklottos.com/openapi.json");
Console.WriteLine(json);

ConnectMeGuru APIhttps://www.connectmeguru.com/api/mcp

using System.Net.Http;

using var http = new HttpClient { Timeout = TimeSpan.FromSeconds(10) };
var json = await http.GetStringAsync("https://www.connectmeguru.com/api/mcp");
Console.WriteLine(json);

Other languages: Python · JavaScript · Node.js · PHP · Java · Go · Ruby

C# API FAQ

How do I call a REST API in C#?

Send an HTTP GET request to the API's URL, check the status code, and parse the JSON body. The working example on this page does exactly that against a live, keyless public API.

Where do I put an API key in C#?

Read it from an environment variable and send it in a header (usually Authorization: Bearer …), never hard-coded or committed to git.

Which free APIs work best with C#?

This page ranks 25 free APIs that suit C#, ordered by ease of access, uptime and developer ratings.