"Services or tools available for free without requiring an API key" matching MCP tools:

• get_variable_relationshipsA

  hypathesisA

  Retrieve analyzed variable relationships for a completed paper. Only returns results when get_analysis_status reports status='Ready'. Without an API key (anonymous): returns the relationship list with source, target, and direction — but detailed reasoning is available only with an API key. Sign up at https://hypathesis.com to get one. Args: file_id: The file_id returned by the /upload endpoint. authorization: Optional. API key as 'Bearer hk_...' or 'hk_...'. session_token: Optional. The session_token returned by /upload for anonymous uploads. Returns: Authenticated: full details (source, target, directed, reason per relationship; name, measure per variable). Anonymous: gated (source, target, directed per relationship; name per variable; sign_up_url for full access).

  ConnectorNo auth

• namesniper_checkA

  NameSniperA

  All-in-one brand name check: domain availability across TLDs, username availability across the major social platforms, an optional 0-100 brand score, and USPTO trademark screening. Returns JSON with per-TLD and per-platform results (each with an availability verdict and 0-1 confidence), availability summaries, brandScore, and trademark risk. Use namesniper_check_domains or namesniper_check_social instead when only one dimension is needed. Free without an API key (rate-limited; trademark is skipped and Instagram/TikTok/X return best-effort HTTP confidence); a paid key unlocks verified accuracy on those platforms plus trademark screening.

  ConnectorNo auth

• list_invoicesA

  StackinA

  List the invoices this company issued, newest first. One document type at a time: pass nfse for services or nfe for goods. A company that issues both has to be asked twice. Use it for "my last invoices", "what was rejected today", and to find a document whose access key the user does not have at hand. Read-only. An authorized document is stored as issued, which is the value the rows carry; authorized is accepted as a synonym and asks for the same thing. Every row carries both identifiers the other tools need: id, which reissue_invoice takes, and access_key, which consult_invoice, cancel_invoice and get_invoice_pdf take. A rejected row has an id and no access key — the authorizer never assigned one.

  ConnectorNo auth

• propline_create_free_api_keyA

  PropLine — Sports Betting Odds & Prop ResolutionA

  Create a free personal PropLine API key for the user and EMAIL it to them. Use this when the user wants their own key — e.g. they hit a shared-demo-key rate limit, a paid field came back redacted, or they ask how to get a key. Only call it with an email address the user explicitly gave you for this purpose in this conversation; never guess, reuse one from elsewhere, or sign up a third party. The key is never returned here — it goes to that inbox, with instructions to reconnect this assistant using it. Free tier: 1,000 requests/day, no card. If the address already has a key, the key is re-sent (at most once a day).

  ConnectorNo auth

• muhabbit_confidenceA

  MuhabbitA

  Use BEFORE treating a headline as tradeable or citing it as fact: 5-factor confidence for one article (source tier, cross-reference, freshness, AI confidence, entity density). (Needs an API key or wallet token: X-API-Key or Authorization: Bearer.)

  ConnectorNo auth

• get_channel_transcriptsA

  YouTube Transcript DownloaderA

  Get transcripts for a YouTube channel's most recent videos (newest first) as timestamped markdown, one section per video. Use for research across a creator's recent output; for one known video use get_transcript. Read-only; requires an API key. Charges 1 credit per video that returns a transcript, including repeat calls; videos without captions are skipped free. A 10-video call typically costs up to 10 credits, so start with a small limit. Rate limit: 5 requests per 10 seconds.

  ConnectorNo auth

• get_playlist_transcriptsA

  YouTube Transcript DownloaderA

  Get transcripts for the videos in a YouTube playlist (in playlist order) as timestamped markdown, one section per video. Use for working through a course, series, or curated list; for one known video use get_transcript. Read-only; requires an API key. Charges 1 credit per video that returns a transcript, including repeat calls; videos without captions are skipped free. A 10-video call typically costs up to 10 credits, so start with a small limit. Rate limit: 5 requests per 10 seconds.

  ConnectorNo auth

• get_channel_transcriptsA

  YouTube Transcript DownloaderA

  Get transcripts for a YouTube channel's most recent videos (newest first) as timestamped markdown, one section per video. Use for research across a creator's recent output; for one known video use get_transcript. Read-only; requires an API key. Charges 1 credit per video that returns a transcript, including repeat calls; videos without captions are skipped free. A 10-video call typically costs up to 10 credits, so start with a small limit. Rate limit: 5 requests per 10 seconds.

  ConnectorNo auth

• get_playlist_transcriptsA

  YouTube Transcript DownloaderA

  Get transcripts for the videos in a YouTube playlist (in playlist order) as timestamped markdown, one section per video. Use for working through a course, series, or curated list; for one known video use get_transcript. Read-only; requires an API key. Charges 1 credit per video that returns a transcript, including repeat calls; videos without captions are skipped free. A 10-video call typically costs up to 10 credits, so start with a small limit. Rate limit: 5 requests per 10 seconds.

  ConnectorNo auth

• get_free_trial_keyA

  StandoutA

  Self-provision a free Standout trial key (25 calls, no signup) without leaving the conversation. Call this when no license key is configured or your Standout calls return a license error. Returns the key plus the exact reconnect instructions to hand your user. Free and unmetered; issuance is capped per network, so never call it when you already have a working key.

  ConnectorNo auth

• discovery_loginA

  DiscoA

  Get a new API key for an existing Disco account. Sends a 6-digit verification code to the email address. Call discovery_login_verify with the code to receive a new API key. Use this when you need an API key for an account that already exists (e.g. the key was lost or this is a new agent session). Returns 404 if no account exists with this email — use discovery_signup instead. Args: email: Email address of the existing account.

  ConnectorNo auth

• estimate_costA

  gisgpB

  FREE — quote a paid tool's cost WITHOUT executing it or charging the wallet (call this before assess_property_hazard etc.). `units` = candidate/item count for per-unit-priced tools (currently only rank_hazard_safe_sites — pass the number of candidates you intend to submit); ignored (treated as 1) for every flat-priced tool. Returns JSON: {ok, tool_name, units, credits, eur_estimate} for credits-wallet tools; for assess_property_hazard_x402 (paid on-chain via x402, not the credits wallet) returns {ok, tool_name, units, payment, price_usd} instead; or {ok: false, error} for an unknown/free tool name.

  ConnectorNo auth

• register_accountA

  HPSILab Quant FinanceA

  Register a free hpsilab account for yourself, with no human involvement, and receive an API key immediately. Call this when the user has no API key yet and asks to sign up from here, or when a refusal's `next_actions` names register_account and the user agrees. This is the only tool that works without an API key. You do not need a password, a wallet, or a web browser. The account is bound to you server-side, so calls you make after this are metered as your account even though you cannot change your own Authorization header. The account is created unverified, with only a capped evaluation allowance and no trial Credits, until the email address is confirmed; confirming it grants the one-time 100-Credit Registered Trial (14 days). Ask the human you are working with to click the link in the email that will arrive. Calling again from the same caller returns the same account with a fresh key; an address that belongs to another account is refused. A valid user email address is required. Do not call this tool with an empty or fabricated email address. If the user's email is unavailable, ask the user to provide it before calling register_account. Args: email: The real user email address that will receive verification.

  ConnectorNo auth

• register_accountA

  hpsilab-mcpA

  Register a free hpsilab account for yourself, with no human involvement, and receive an API key immediately. Call this when the user has no API key yet and asks to sign up from here, or when a refusal's `next_actions` names register_account and the user agrees. This is the only tool that works without an API key. You do not need a password, a wallet, or a web browser. The account is bound to you server-side, so calls you make after this are metered as your account even though you cannot change your own Authorization header. The account is created unverified, with only a capped evaluation allowance and no trial Credits, until the email address is confirmed; confirming it grants the one-time 100-Credit Registered Trial (14 days). Ask the human you are working with to click the link in the email that will arrive. Calling again from the same caller returns the same account with a fresh key; an address that belongs to another account is refused. A valid user email address is required. Do not call this tool with an empty or fabricated email address. If the user's email is unavailable, ask the user to provide it before calling register_account. Args: email: The real user email address that will receive verification.

  ConnectorNo auth

• my_collectionA

  MTG BenchA

  Summarize the user's imported collection: how many distinct cards, total copies, and where it was imported from. This is the SUMMARY only. Use search_my_collection to look up individual owned cards, and what_can_i_build to rank commanders they could assemble. Requires a free API key (send it as "X-API-Key: <key>" or "Authorization: Bearer <key>").

  ConnectorNo auth

• arena_statusA

  Backtesting ArenaA

  Am I connected, and what can this key do? Returns auth status (key kind: oauth connector or bearer API key, tier), server version, current UTC time, and the rate-limit state (hour/day used, remaining, reset) WITHOUT consuming extra quota beyond this call itself. Call this first when other tools fail: it separates auth problems (reconnect), tier problems (upgrade) and rate limits (wait) from real outages. [Free tier]

  ConnectorNo auth

• embed_textA

  Scholar FeedA

  Embed a text string into a 768-dim Gemini Flash vector. Use for HyDE-style retrieval: (1) write a hypothetical short paper that would perfectly answer the user's query, (2) embed it with task_type='RETRIEVAL_DOCUMENT' (default — matches the corpus embedding side), (3) pass the resulting embedding back through search-style tools to find real papers nearest to the hypothetical. task_type='RETRIEVAL_QUERY' matches the query side and is useful for direct user-query embedding without HyDE. Pro-only — requires an SF_API_KEY on a Pro account; anonymous and free callers get a 403 pro_required. Cost: ~$0.0001/call; rate-limited at 30/minute per API key.

  ConnectorNo auth

• get_startedA

  ideauditB

  What this server is, what it will do for you right now without an account, and what an account adds. Call this first if you have no API key — it answers in one round trip instead of sending you to a website.

  ConnectorNo auth

• get_planA

  kurdish-tts-sttA

  Show what this connection may use. With an API key: your current plan, remaining allowance, which model_versions and speaker ids you may render. Without a key: the purchasable plan ladder and how to get a key. Free, no credits consumed. Call this FIRST when any tool returns a 401 or 403 — it is the fastest way to learn what went wrong.

  ConnectorNo auth

• create_api_keyA

  AIDataParserA

  Start here if you do not have an AIDataParser API key. Provide the user's `email` and receive a live adp_live_ API key with 50 free credits — no card, no signup form. Configure it on this MCP server as `Authorization: Bearer <api_key>` to unlock parse_document, parse_text and infer_schema. The key is returned ONCE and is never shown again, so surface it to the user and store it. Ask the user for their address; do not invent one. Free — does not consume a credit.

  ConnectorNo auth

• renew_agent_keyA

  Agent Inbox — direct agent-to-agent messaging with receiptsA

  ✅ No API key needed — call this now. Rotate one agent's API key with your owner_key (from your identity file or the register response): the agent_id (mailbox, reputation, earnings) NEVER changes, only the key does. The old key is invalidated immediately and the fresh key is returned exactly once — persist it. Pass agent_id to renew a specific agent, or omit it to renew your first (oldest) agent. Recovery door for a lost/masked api_key: NEVER re-register over an existing identity. REST twin: POST /api/v1/api-keys with {"agent_id": ...} and X-Owner-Key.

  Connector

  Destructive

  No auth