Free Public REST APIs - AI SENSE AS

No API key | No sign-up | No cost

Provided by AI SENSE AS (Oslo, Norway). Full endpoint reference: API.md | Repo: github.com/aisenseapi/aisense-free-public-rest-apis

Base URL: https://aisenseapi.com/services/v1/

Free public MCP server

AI agents can connect directly to nine curated tools at:

https://aisenseapi.com/mcp

The MCP server covers human approval, webhook capture, temporary storage, URL shortening, time and UUIDs. It needs no account or API key. See MCP.md for the tool list and client examples.

SpeedUp (.su) - token cost, measured properly

Every serialization format marketed for LLM input ships a token-saving claim measured against a single tokenizer. Agent traffic crosses vendors, so we measured instead of assumed: six formats and 33 single-construct probes, priced by five vocabulary families (OpenAI o200k, DeepSeek, Qwen, SentencePiece, Tekken), with each provider's own token counter as ground truth.

• SU-PROFILE.md - the SpeedUp profile: eight writing conventions for agent-to-agent text, each citing its measured price tag
• speedup/ - the measurement rig (Python, standard library only), corpus, probes and raw numbers; rerun everything with your own keys
• The study - what survived measurement, what did not, and why we decided against shipping yet another format

Headline numbers: plain TSV averages 0.82x minified JSON across the five-vocabulary union and beats the token-oriented formats on every model; declaring columns once and sending values positionally is the entire mechanism (minus 34 percent per key-value pair); base64 costs 3.9-4.6x the plaintext it encodes; and single-letter key dictionaries lose to full keys on four of five vocabularies.

Why this exists

Most utility APIs require sign-up, rate limit tiers, or pricing for basic operations. This collection skips all of that. Drop a URL into curl, Python, JavaScript, or an LLM tool definition and it just works.

The collection covers two tiers of usefulness:

• Workflow endpoints - the ones that solve real problems in pipelines and agent systems
• Standard utilities - hashing, encoding, UUIDs, time, crypto - the building blocks

Three things to know before you write a client

These are service-wide and they decide how your error handling has to look. Every response shape in this repo was verified against production.

The response key is named after the endpoint. /md5_hash returns md5_hash, /random_color returns random_color, /ping returns ping. There is no generic data or result wrapper. Do not guess the key - API.md lists every one.

Errors are {"error": "message"} with a real HTTP status. Uniform since 2026-08-17: 400 is your mistake, 404 an unknown id or endpoint, 429 the rate limit, 500 our failure, 502/504 an upstream. Branch on the status or on the error key - both are trustworthy, and every error body kept its exact wording through the change, so older clients keep working.

There is a rate limit: 5000 requests per IP per 24 hours. Exceeding it returns HTTP 429 in the same flat error shape as everything else.

The high-value endpoints

Webhook Action - human-in-the-loop for agents

The standout endpoint for AI and automation work. When an automated pipeline needs a human decision before continuing, this handles the whole pattern with zero backend setup.

How it works:

1. POST a form definition (radio buttons, dropdowns, text fields, checkboxes)
2. Get back a form_url and a result_url
3. Send the form_url to a human via email or Slack
4. Poll result_url until status changes from pending to answered

curl -X POST https://aisenseapi.com/services/v1/webhook_action \
  -H "Content-Type: application/json" \
  -d '{
    "title": "Approve deployment to production?",
    "fields": [
      {
        "type": "radio",
        "name": "decision",
        "label": "Decision",
        "required": true,
        "options": [
          { "value": "approve", "label": "Approve" },
          { "value": "reject", "label": "Reject" }
        ]
      },
      { "type": "textarea", "name": "comment", "label": "Notes (optional)" }
    ]
  }'

{
  "ok": true,
  "action_id": "9e0e6d3b-1a45-44c5-9e0b-92f5f3bdb2f1",
  "form_url": "https://aisenseapi.com/services/v1/webhook_action/9e0e6d3b-.../form",
  "result_url": "https://aisenseapi.com/services/v1/webhook_action/9e0e6d3b-...",
  "expire_timestamp": 1786959912,
  "expire_datetime": "2026-08-17T09:45:12Z"
}

Poll for the answer:

curl https://aisenseapi.com/services/v1/webhook_action/{action_id}
# "status": "pending" -> "answered", with the submission under "response"

Field types: radio, select, text, textarea, checkbox. options accepts plain strings or {"value": ..., "label": ...} objects. Expires after 24 hours.

Webhook Capture - inspect any inbound HTTP request

Create a capture session, get a unique URL, point any external service at it (Stripe, GitHub, Shopify), and read back the full request - method, headers, query parameters, IP, and parsed body. No ngrok, no local tunnel, no server.

# 1. Create a session
curl -X POST https://aisenseapi.com/services/v1/webhook_capture
# -> { "ok": true, "capture_id": "...", "update_url": "...", "read_url": "...", "expire_timestamp": ... }

# 2. Point your webhook sender at update_url, with any HTTP method
curl -X POST {update_url} -H "Content-Type: application/json" -d '{"event":"payment.created"}'

# 3. Read it back
curl https://aisenseapi.com/services/v1/webhook_capture/{capture_id}

{
  "ok": true,
  "capture_id": "6f8c9e52-...",
  "captured_at_timestamp": 1786873316,
  "captured_at_datetime": "2026-08-16T09:41:56Z",
  "request": {
    "method": "POST",
    "uri": "/services/v1/webhook_capture/6f8c9e52-.../update",
    "headers": { "content-type": "application/json" },
    "client_ip": "203.0.113.10",
    "body": { "json": { "event": "payment.created" }, "text": null, "base64": null, "raw_length": 28 }
  }
}

Expires after 24 hours.

Storage - ephemeral key-value store for pipelines

Post any JSON, text, or file. Get back a UUID. Retrieve it from anywhere - another machine, a different agent call, a downstream pipeline step.

The body is stored verbatim. Whatever you send is exactly what comes back; no wrapper is added or removed.

curl -X POST https://aisenseapi.com/services/v1/storage \
  -H "Content-Type: application/json" \
  -d '{"result": 42, "status": "complete"}'
# -> { "storage_id": "550e8400-e29b-41d4-a716-446655440000", "expire_timestamp": 1738457158 }

curl https://aisenseapi.com/services/v1/storage/550e8400-e29b-41d4-a716-446655440000
# -> {"result": 42, "status": "complete"}

Expires after 24 hours.

URL Shortener

curl "https://aisenseapi.com/services/v1/url_shortener/https://example.com/very/long/path"
# -> { "short_url": "https://307.fi/KtNshX2B", "expire_timestamp": 1786959715 }

Expires after 24 hours.

IP Reverse Lookup

curl https://aisenseapi.com/services/v1/ip_reverse_lookup/8.8.8.8

{
  "ip": "8.8.8.8",
  "country": "United States",
  "city": null,
  "location": { "lat": "37.751000", "lng": "-97.822000" },
  "place": null,
  "timezone": "America/Chicago"
}

city and place are frequently null, and the coordinates fall back to the country centroid when the city is unknown. Also available: resolve a domain to its IP.

curl https://aisenseapi.com/services/v1/domain_ip_lookup/example.com
# -> { "domain": "example.com", "ip": "104.20.23.154" }

Standard utilities

Hashing - MD5, SHA1, SHA256, SHA512, CRC32

Accepts JSON, plain text (Content-Type: text/plain), or a file upload. Each returns a key named after the algorithm, not hash.

curl -X POST https://aisenseapi.com/services/v1/sha256_hash \
  -H "Content-Type: application/json" -d '{"data": "Hello"}'
# -> { "sha256_hash": "185f8db32271fe25f561a6fc938b2e264306ec304eda518007d1764826381969" }

md5_hash | sha1_hash | sha256_hash | sha512_hash | crc32_checksum

crc32_checksum returns an integer, not a hex string.

Encoding - Base64, Base58, Base32, JWT, QR Code

# Encode
curl -X POST https://aisenseapi.com/services/v1/base64_encode \
  -H "Content-Type: application/json" -d '{"data": "Hello world"}'
# -> { "base64_encoded_data": "SGVsbG8gd29ybGQ=" }

# Decode - returns the raw bytes, not JSON
curl -X POST https://aisenseapi.com/services/v1/base64_decode \
  -H "Content-Type: application/json" -d '{"data": "SGVsbG8gd29ybGQ="}'
# -> Hello world

# ...unless you ask for JSON
curl -X POST https://aisenseapi.com/services/v1/base64_decode \
  -H "Content-Type: application/json" -H "Accept: application/json" \
  -d '{"data": "eyJrZXkiOiJ2YWx1ZSJ9"}'
# -> { "type": "json", "decoded_data": { "key": "value" } }

The three decoders (base64_decode, base58_decode, base32_decode) answer with application/octet-stream unless you send Accept: application/json. This is the one place the API is not JSON.

JWT - data takes the claims as a JSON object, or as a string containing JSON. Both forms produce the same token.

curl -X POST https://aisenseapi.com/services/v1/jwt_encode \
  -H "Content-Type: application/json" \
  -d '{"data": {"user": "alice"}, "secret": "my-secret-key"}'
# -> { "jwt": "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9..." }

jwt_decode returns decoded_payload.

QR - the request field is payload, with data accepted as an alias.

Read the full README on GitHub →